Make the check<T>() function more flexible (so that it doesn't always

just return a 'undefined' RuntimeError).
Other small improvements.

src/tickable.ts

@@ -33,7 +33,7 @@ export interface FormatterMetrics {
  */
 export abstract class Tickable extends Element {
   protected ignore_ticks: boolean;
-  tupletStack: Tuplet[];
+  protected tupletStack: Tuplet[];
   protected tuplet?: Tuplet;
   protected ticks: Fraction;
   protected center_x_shift: number;
@@ -118,8 +118,9 @@ export abstract class Tickable extends Element {
   }
 
   /** Ignore the ticks. */
-  setIgnoreTicks(flag: boolean): void {
+  setIgnoreTicks(flag: boolean): this {
     this.ignore_ticks = flag;
+    return this;
   }
 
   /** Set width of note. Used by the formatter for positioning. */
@@ -206,6 +207,11 @@ export abstract class Tickable extends Element {
     return this.tuplet;
   }
 
+  /** Return the intrinsic ticks. */
+  getTupletStack(): Tuplet[] {
+    return this.tupletStack;
+  }
+
   /*
    * Reset the specific Tuplet if this is not provided, all tuplets are reset.
    * Remove any prior tuplets from the tick calculation and

src/tickcontext.ts

@@ -19,8 +19,7 @@ export interface TickContextOptions {
 }
 
 /**
- * Tickcontext formats abstract tickable objects, such as notes, chords,
- * tabs, etc.
+ * TickContext formats abstract tickable objects, such as notes, chords, tabs, etc.
  */
 export class TickContext extends Tickable {
   protected readonly tickID: number;
@@ -46,7 +45,7 @@ export class TickContext extends Tickable {
   tContexts: TickContext[];
 
   // eslint-disable-next-line
-  draw() {}
+  draw(...args: any[]): void {}
 
   static getNextContext(tContext: TickContext): TickContext | undefined {
     const contexts = tContext.tContexts;

src/tuplet.ts

@@ -238,7 +238,7 @@ export class Tuplet extends Element {
     // Count the tuplets that are on the same side (above/below)
     // as this tuplet:
     function countTuplets(note: Note, location: number) {
-      return note.tupletStack.filter((tuplet) => tuplet.location === location).length;
+      return note.getTupletStack().filter((tuplet) => tuplet.location === location).length;
     }
 
     this.notes.forEach((note) => {

src/util.ts

@@ -12,10 +12,13 @@ export class RuntimeError extends Error {
   }
 }
 
-/** Check that `x` is of type `T` and not `undefined`. */
-export function check<T>(x?: T): T {
+/**
+ * Check that `x` is of type `T` and not `undefined`.
+ * If `x` is `undefined`, throw a RuntimeError with the optionally provided error code and message.
+ */
+export function check<T>(x?: T, code: string = 'undefined', message: string = ''): T {
   if (x === undefined) {
-    throw new RuntimeError('undefined');
+    throw new RuntimeError(code, message);
   }
   return x;
 }