diff --git a/src/document/crdt/element_rht.ts b/src/document/crdt/element_rht.ts
index 53aff4d2e..2c36081b2 100644
--- a/src/document/crdt/element_rht.ts
+++ b/src/document/crdt/element_rht.ts
@@ -115,9 +115,9 @@ export class ElementRHT {
    */
   public delete(createdAt: TimeTicket, executedAt: TimeTicket): CRDTElement {
     if (!this.nodeMapByCreatedAt.has(createdAt.toIDString())) {
-      const ERROR_MESSAGE = `fail to find ${createdAt.toIDString()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to find ${createdAt.toIDString()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     const node = this.nodeMapByCreatedAt.get(createdAt.toIDString())!;
@@ -145,11 +145,11 @@ export class ElementRHT {
       element.getCreatedAt().toIDString(),
     );
     if (!node) {
-      const ERROR_MESSAGE = `fail to find ${element
+      const ErrorMessage = `fail to find ${element
         .getCreatedAt()
         .toIDString()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     const nodeByKey = this.nodeMapByKey.get(node.getStrKey());
diff --git a/src/document/crdt/rga_tree_list.ts b/src/document/crdt/rga_tree_list.ts
index 156775eb2..16146b236 100644
--- a/src/document/crdt/rga_tree_list.ts
+++ b/src/document/crdt/rga_tree_list.ts
@@ -181,9 +181,9 @@ export class RGATreeList {
   ): RGATreeListNode {
     let node = this.nodeMapByCreatedAt.get(createdAt.toIDString());
     if (!node) {
-      const ERROR_MESSAGE = `cant find the given node: ${createdAt.toIDString()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `cant find the given node: ${createdAt.toIDString()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     while (
@@ -235,16 +235,16 @@ export class RGATreeList {
   ): void {
     const prevNode = this.nodeMapByCreatedAt.get(prevCreatedAt.toIDString());
     if (!prevNode) {
-      const ERROR_MESSAGE = `cant find the given node: ${prevCreatedAt.toIDString()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `cant find the given node: ${prevCreatedAt.toIDString()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     const node = this.nodeMapByCreatedAt.get(createdAt.toIDString());
     if (!node) {
-      const ERROR_MESSAGE = `cant find the given node: ${createdAt.toIDString()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `cant find the given node: ${createdAt.toIDString()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     if (
@@ -291,11 +291,11 @@ export class RGATreeList {
       element.getCreatedAt().toIDString(),
     );
     if (!node) {
-      const ERROR_MESSAGE = `fail to find the given createdAt: ${element
+      const ErrorMessage = `fail to find the given createdAt: ${element
         .getCreatedAt()
         .toIDString()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     this.release(node!);
   }
diff --git a/src/document/crdt/rga_tree_split.ts b/src/document/crdt/rga_tree_split.ts
index 122788878..4c2558f45 100644
--- a/src/document/crdt/rga_tree_split.ts
+++ b/src/document/crdt/rga_tree_split.ts
@@ -635,9 +635,9 @@ export class RGATreeSplit<T extends RGATreeSplitValue> implements GCParent {
       ? this.findFloorNodePreferToLeft(absoluteID)
       : this.findFloorNode(absoluteID);
     if (!node) {
-      const ERROR_MESSAGE = `the node of the given id should be found: ${absoluteID.toTestString()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `the node of the given id should be found: ${absoluteID.toTestString()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     const index = this.treeByIndex.indexOf(node!);
     const offset = node!.isRemoved()
@@ -794,9 +794,9 @@ export class RGATreeSplit<T extends RGATreeSplitValue> implements GCParent {
   ): RGATreeSplitNode<T> {
     let node = this.findFloorNode(id);
     if (!node) {
-      const ERROR_MESSAGE = `the node of the given id should be found: ${id.toTestString()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `the node of the given id should be found: ${id.toTestString()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     if (id.getOffset() > 0 && node!.getID().getOffset() == id.getOffset()) {
@@ -848,9 +848,9 @@ export class RGATreeSplit<T extends RGATreeSplitValue> implements GCParent {
     offset: number,
   ): RGATreeSplitNode<T> | undefined {
     if (offset > node.getContentLength()) {
-      const ERROR_MESSAGE = `offset should be less than or equal to length`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `offset should be less than or equal to length`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     if (offset === 0) {
diff --git a/src/document/crdt/root.ts b/src/document/crdt/root.ts
index 4dea28e23..2a31907d7 100644
--- a/src/document/crdt/root.ts
+++ b/src/document/crdt/root.ts
@@ -135,9 +135,9 @@ export class CRDTRoot {
       const createdAt = pair.element.getCreatedAt();
       const subPath = pair.parent.subPathOf(createdAt);
       if (subPath === undefined) {
-        const ERROR_MESSAGE = `cant find the given element: ${createdAt.toIDString()}`;
-        logger.fatal(ERROR_MESSAGE);
-        throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+        const ErrorMessage = `cant find the given element: ${createdAt.toIDString()}`;
+        logger.fatal(ErrorMessage);
+        throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
       }
 
       subPaths.unshift(subPath!);
diff --git a/src/document/json/counter.ts b/src/document/json/counter.ts
index b3bf65094..f7333de72 100644
--- a/src/document/json/counter.ts
+++ b/src/document/json/counter.ts
@@ -79,9 +79,9 @@ export class Counter {
    */
   public increase(v: number | Long): Counter {
     if (!this.context || !this.counter) {
-      const ERROR_MESSAGE = 'Counter is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Counter is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     const ticket = this.context.issueTimeTicket();
diff --git a/src/document/json/text.ts b/src/document/json/text.ts
index f341e8e06..783a64a3b 100644
--- a/src/document/json/text.ts
+++ b/src/document/json/text.ts
@@ -93,15 +93,15 @@ export class Text<A extends Indexable = Indexable> {
     attributes?: A,
   ): [number, number] | undefined {
     if (!this.context || !this.text) {
-      const ERROR_MESSAGE = 'Text is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Text is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     if (fromIdx > toIdx) {
-      const ERROR_MESSAGE = 'from should be less than or equal to to';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = 'from should be less than or equal to to';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     const range = this.text.indexRangeToPosRange(fromIdx, toIdx);
@@ -157,15 +157,15 @@ export class Text<A extends Indexable = Indexable> {
    */
   setStyle(fromIdx: number, toIdx: number, attributes: A): boolean {
     if (!this.context || !this.text) {
-      const ERROR_MESSAGE = 'Text is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Text is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     if (fromIdx > toIdx) {
-      const ERROR_MESSAGE = 'from should be less than or equal to to';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = 'from should be less than or equal to to';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     const range = this.text.indexRangeToPosRange(fromIdx, toIdx);
@@ -208,9 +208,9 @@ export class Text<A extends Indexable = Indexable> {
    */
   indexRangeToPosRange(range: [number, number]): TextPosStructRange {
     if (!this.context || !this.text) {
-      const ERROR_MESSAGE = 'Text is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Text is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     const textRange = this.text.indexRangeToPosRange(range[0], range[1]);
@@ -222,9 +222,9 @@ export class Text<A extends Indexable = Indexable> {
    */
   posRangeToIndexRange(range: TextPosStructRange): [number, number] {
     if (!this.context || !this.text) {
-      const ERROR_MESSAGE = 'Text is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Text is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     const textRange = this.text.findIndexesFromRange([
@@ -240,9 +240,9 @@ export class Text<A extends Indexable = Indexable> {
    */
   toTestString(): string {
     if (!this.context || !this.text) {
-      const ERROR_MESSAGE = 'Text is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Text is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     return this.text.toTestString();
@@ -253,9 +253,9 @@ export class Text<A extends Indexable = Indexable> {
    */
   values(): Array<TextValueType<A>> {
     if (!this.context || !this.text) {
-      const ERROR_MESSAGE = 'Text is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Text is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     return this.text.values();
@@ -290,9 +290,9 @@ export class Text<A extends Indexable = Indexable> {
    */
   toString(): string {
     if (!this.context || !this.text) {
-      const ERROR_MESSAGE = 'Text is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Text is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     return this.text.toString();
@@ -333,9 +333,9 @@ export class Text<A extends Indexable = Indexable> {
    */
   createRangeForTest(fromIdx: number, toIdx: number): RGATreeSplitPosRange {
     if (!this.context || !this.text) {
-      const ERROR_MESSAGE = 'Text is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Text is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     return this.text.indexRangeToPosRange(fromIdx, toIdx);
diff --git a/src/document/json/tree.ts b/src/document/json/tree.ts
index 9e15f9cac..983da2987 100644
--- a/src/document/json/tree.ts
+++ b/src/document/json/tree.ts
@@ -739,9 +739,9 @@ export class Tree {
     range: [Array<number>, Array<number>],
   ): TreePosStructRange {
     if (!this.context || !this.tree) {
-      const ERROR_MESSAGE = 'Tree is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Tree is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     const indexRange: [number, number] = [
@@ -757,9 +757,9 @@ export class Tree {
    */
   indexRangeToPosRange(range: [number, number]): TreePosStructRange {
     if (!this.context || !this.tree) {
-      const ERROR_MESSAGE = 'Tree is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Tree is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     return this.tree.indexRangeToPosStructRange(range);
@@ -770,9 +770,9 @@ export class Tree {
    */
   posRangeToIndexRange(range: TreePosStructRange): [number, number] {
     if (!this.context || !this.tree) {
-      const ERROR_MESSAGE = 'Tree is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Tree is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     const posRange: [CRDTTreePos, CRDTTreePos] = [
@@ -790,9 +790,9 @@ export class Tree {
     range: TreePosStructRange,
   ): [Array<number>, Array<number>] {
     if (!this.context || !this.tree) {
-      const ERROR_MESSAGE = 'Tree is not initialized yet';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotReady, ERROR_MESSAGE);
+      const ErrorMessage = 'Tree is not initialized yet';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotReady, ErrorMessage);
     }
 
     const posRange: [CRDTTreePos, CRDTTreePos] = [
diff --git a/src/document/operation/add_operation.ts b/src/document/operation/add_operation.ts
index 9167c3897..3526b7e3a 100644
--- a/src/document/operation/add_operation.ts
+++ b/src/document/operation/add_operation.ts
@@ -61,14 +61,14 @@ export class AddOperation extends Operation {
   public execute(root: CRDTRoot): ExecutionResult {
     const parentObject = root.findByCreatedAt(this.getParentCreatedAt());
     if (!parentObject) {
-      const ERROR_MESSAGE = `fail to find ${this.getParentCreatedAt()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to find ${this.getParentCreatedAt()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     if (!(parentObject instanceof CRDTArray)) {
-      const ERROR_MESSAGE = `fail to execute, only array can execute add`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to execute, only array can execute add`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     const array = parentObject as CRDTArray;
     const value = this.value.deepcopy();
diff --git a/src/document/operation/edit_operation.ts b/src/document/operation/edit_operation.ts
index d86479473..491d6314d 100644
--- a/src/document/operation/edit_operation.ts
+++ b/src/document/operation/edit_operation.ts
@@ -84,14 +84,14 @@ export class EditOperation extends Operation {
   public execute<A extends Indexable>(root: CRDTRoot): ExecutionResult {
     const parentObject = root.findByCreatedAt(this.getParentCreatedAt());
     if (!parentObject) {
-      const ERROR_MESSAGE = `fail to find ${this.getParentCreatedAt()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to find ${this.getParentCreatedAt()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     if (!(parentObject instanceof CRDTText)) {
-      const ERROR_MESSAGE = `fail to execute, only Text can execute edit`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to execute, only Text can execute edit`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     const text = parentObject as CRDTText<A>;
diff --git a/src/document/operation/increase_operation.ts b/src/document/operation/increase_operation.ts
index 01d519f00..7dab3bcb0 100644
--- a/src/document/operation/increase_operation.ts
+++ b/src/document/operation/increase_operation.ts
@@ -63,14 +63,14 @@ export class IncreaseOperation extends Operation {
   public execute(root: CRDTRoot): ExecutionResult {
     const parentObject = root.findByCreatedAt(this.getParentCreatedAt());
     if (!parentObject) {
-      const ERROR_MESSAGE = `fail to find ${this.getParentCreatedAt()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to find ${this.getParentCreatedAt()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     if (!(parentObject instanceof CRDTCounter)) {
-      const ERROR_MESSAGE = `fail to execute, only Counter can execute increase`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to execute, only Counter can execute increase`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     const counter = parentObject as CRDTCounter;
     const value = this.value.deepcopy() as Primitive;
diff --git a/src/document/operation/move_operation.ts b/src/document/operation/move_operation.ts
index 873d11860..2b8573136 100644
--- a/src/document/operation/move_operation.ts
+++ b/src/document/operation/move_operation.ts
@@ -65,14 +65,14 @@ export class MoveOperation extends Operation {
   public execute(root: CRDTRoot): ExecutionResult {
     const parentObject = root.findByCreatedAt(this.getParentCreatedAt());
     if (!parentObject) {
-      const ERROR_MESSAGE = `fail to find ${this.getParentCreatedAt()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to find ${this.getParentCreatedAt()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     if (!(parentObject instanceof CRDTArray)) {
-      const ERROR_MESSAGE = `fail to execute, only array can execute move`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to execute, only array can execute move`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     const array = parentObject as CRDTArray;
     const previousIndex = Number(array.subPathOf(this.createdAt));
diff --git a/src/document/operation/remove_operation.ts b/src/document/operation/remove_operation.ts
index 8a52a73e0..5b92043c3 100644
--- a/src/document/operation/remove_operation.ts
+++ b/src/document/operation/remove_operation.ts
@@ -69,14 +69,14 @@ export class RemoveOperation extends Operation {
       this.getParentCreatedAt(),
     ) as CRDTContainer;
     if (!container) {
-      const ERROR_MESSAGE = `fail to find ${this.getParentCreatedAt()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to find ${this.getParentCreatedAt()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     if (!(container instanceof CRDTContainer)) {
-      const ERROR_MESSAGE = `only object and array can execute remove: ${container}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `only object and array can execute remove: ${container}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     // NOTE(chacha912): Handle cases where operation cannot be executed during undo and redo.
diff --git a/src/document/operation/set_operation.ts b/src/document/operation/set_operation.ts
index 1c22ce7b0..2c32769ee 100644
--- a/src/document/operation/set_operation.ts
+++ b/src/document/operation/set_operation.ts
@@ -67,14 +67,14 @@ export class SetOperation extends Operation {
   ): ExecutionResult | undefined {
     const obj = root.findByCreatedAt(this.getParentCreatedAt()) as CRDTObject;
     if (!obj) {
-      const ERROR_MESSAGE = `fail to find ${this.getParentCreatedAt()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to find ${this.getParentCreatedAt()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     if (!(obj instanceof CRDTObject)) {
-      const ERROR_MESSAGE = `fail to execute, only object can execute set`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to execute, only object can execute set`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     // NOTE(chacha912): Handle cases where operation cannot be executed during undo and redo.
diff --git a/src/document/operation/style_operation.ts b/src/document/operation/style_operation.ts
index 0d815e311..ab5945a38 100644
--- a/src/document/operation/style_operation.ts
+++ b/src/document/operation/style_operation.ts
@@ -78,14 +78,14 @@ export class StyleOperation extends Operation {
   public execute<A extends Indexable>(root: CRDTRoot): ExecutionResult {
     const parentObject = root.findByCreatedAt(this.getParentCreatedAt());
     if (!parentObject) {
-      const ERROR_MESSAGE = `fail to find ${this.getParentCreatedAt()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to find ${this.getParentCreatedAt()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     if (!(parentObject instanceof CRDTText)) {
-      const ERROR_MESSAGE = `fail to execute, only Text can execute edit`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to execute, only Text can execute edit`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     const text = parentObject as CRDTText<A>;
     const [, pairs, changes] = text.setStyle(
diff --git a/src/document/operation/tree_edit_operation.ts b/src/document/operation/tree_edit_operation.ts
index 86f1f92af..662566586 100644
--- a/src/document/operation/tree_edit_operation.ts
+++ b/src/document/operation/tree_edit_operation.ts
@@ -86,14 +86,14 @@ export class TreeEditOperation extends Operation {
   public execute(root: CRDTRoot): ExecutionResult {
     const parentObject = root.findByCreatedAt(this.getParentCreatedAt());
     if (!parentObject) {
-      const ERROR_MESSAGE = `fail to find ${this.getParentCreatedAt()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to find ${this.getParentCreatedAt()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     if (!(parentObject instanceof CRDTTree)) {
-      const ERROR_MESSAGE = `fail to execute, only Tree can execute edit`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to execute, only Tree can execute edit`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     const editedAt = this.getExecutedAt();
     const tree = parentObject as CRDTTree;
diff --git a/src/document/operation/tree_style_operation.ts b/src/document/operation/tree_style_operation.ts
index 7dfe5852a..65b0e68d9 100644
--- a/src/document/operation/tree_style_operation.ts
+++ b/src/document/operation/tree_style_operation.ts
@@ -108,14 +108,14 @@ export class TreeStyleOperation extends Operation {
   public execute(root: CRDTRoot): ExecutionResult {
     const parentObject = root.findByCreatedAt(this.getParentCreatedAt());
     if (!parentObject) {
-      const ERROR_MESSAGE = `fail to find ${this.getParentCreatedAt()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to find ${this.getParentCreatedAt()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     if (!(parentObject instanceof CRDTTree)) {
-      const ERROR_MESSAGE = `fail to execute, only Tree can execute edit`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `fail to execute, only Tree can execute edit`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     const tree = parentObject as CRDTTree;
     let changes: Array<TreeChange>;
diff --git a/src/util/observable.ts b/src/util/observable.ts
index 810773af7..efe35883c 100644
--- a/src/util/observable.ts
+++ b/src/util/observable.ts
@@ -107,15 +107,15 @@ class ObserverProxy<T> implements Observer<T> {
     let observer: Observer<T>;
 
     if (!nextOrObserver) {
-      const ERROR_MESSAGE = 'missing observer';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = 'missing observer';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
 
     if (this.finalized) {
-      const ERROR_MESSAGE = 'observable is finalized due to previous error';
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrOperationNotPermitted, ERROR_MESSAGE);
+      const ErrorMessage = 'observable is finalized due to previous error';
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrOperationNotPermitted, ErrorMessage);
     }
 
     if (typeof nextOrObserver === 'object') {
diff --git a/src/util/splay_tree.ts b/src/util/splay_tree.ts
index 888d1b2bf..bac9c38e6 100644
--- a/src/util/splay_tree.ts
+++ b/src/util/splay_tree.ts
@@ -207,9 +207,9 @@ export class SplayTree<V> {
       }
     }
     if (pos > node.getLength()) {
-      const ERROR_MESSAGE = `out of index range: pos: ${pos} > node.length: ${node.getLength()}`;
-      logger.fatal(ERROR_MESSAGE);
-      throw new YorkieError(Code.ErrInvalidArgument, ERROR_MESSAGE);
+      const ErrorMessage = `out of index range: pos: ${pos} > node.length: ${node.getLength()}`;
+      logger.fatal(ErrorMessage);
+      throw new YorkieError(Code.ErrInvalidArgument, ErrorMessage);
     }
     return [node, pos];
   }
diff --git a/test/integration/primitive_test.ts b/test/integration/primitive_test.ts
index 575c0ce4a..5211cb29c 100644
--- a/test/integration/primitive_test.ts
+++ b/test/integration/primitive_test.ts
@@ -36,11 +36,11 @@ describe('Primitive', function () {
     });
     assert.equal('{"k1":{"k1-1":1,"k1-2":2}}', doc.toSortedJSON());
     assert.throws(() => {
-      const ERROR_MESSAGE = 'dummy error';
+      const ErrorMessage = 'dummy error';
       doc.update((root) => {
         delete root['k1']['k1-1'];
-        throw new YorkieError(Code.ErrDummy, ERROR_MESSAGE);
-      }, ERROR_MESSAGE);
+        throw new YorkieError(Code.ErrDummy, ErrorMessage);
+      }, ErrorMessage);
     });
     assert.equal('{"k1":{"k1-1":1,"k1-2":2}}', doc.toSortedJSON());
   });