ref: Leave only valid buffer implementation

packages/utils/src/promisebuffer.ts

@@ -1,9 +1,6 @@
 import { SentryError } from './error';
-import { isThenable } from './is';
 import { SyncPromise } from './syncpromise';
 
-type TaskProducer<T> = () => PromiseLike<T>;
-
 /** A simple queue that holds promises. */
 export class PromiseBuffer<T> {
   /** Internal set of queued Promises */
@@ -21,22 +18,14 @@ export class PromiseBuffer<T> {
   /**
    * Add a promise to the queue.
    *
-   * @param taskProducer A function producing any PromiseLike<T>; In previous versions this used to be `@param task: PromiseLike<T>`, however, Promises were instantly created on the call-site, making them fall through the buffer limit.
+   * @param taskProducer A function producing any PromiseLike<T>.
    * @returns The original promise.
    */
-  public add(taskProducer: PromiseLike<T> | TaskProducer<T>): PromiseLike<T> {
-    // NOTE: This is necessary to preserve backwards compatibility
-    // It should accept _only_ `TaskProducer<T>` but we dont want to break other custom transports
-    // that are utilizing our `Buffer` implementation.
-    // see: https://github.com/getsentry/sentry-javascript/issues/3725
-    const normalizedTaskProducer: TaskProducer<T> = isThenable(taskProducer)
-      ? () => taskProducer as PromiseLike<T>
-      : (taskProducer as TaskProducer<T>);
-
+  public add(taskProducer: () => PromiseLike<T>): PromiseLike<T> {
     if (!this.isReady()) {
       return SyncPromise.reject(new SentryError('Not adding Promise due to buffer limit reached.'));
     }
-    const task = normalizedTaskProducer();
+    const task = taskProducer();
     if (this._buffer.indexOf(task) === -1) {
       this._buffer.push(task);
     }