Upgrade to TypeScript 4.

RubenVerborgh · RubenVerborgh · commit a536bca2dfe8 · 2022-06-24T17:44:03.000+01:00
diff --git a/asynciterator.ts b/asynciterator.ts
@@ -1241,7 +1241,7 @@ export class TransformIterator<S, D = S> extends BufferedIterator<D> {
 }
 
 function destinationEmitError<S>(this: InternalSource<S>, error: Error) {
-  this._destination.emit('error', error);
+  this._destination!.emit('error', error);
 }
 function destinationCloseWhenDone<S>(this: InternalSource<S>) {
   (this._destination as any)._closeWhenDone();
@@ -1985,4 +1985,4 @@ type SourceExpression<T> =
   (() => MaybePromise<AsyncIterator<T>>);
 
 type InternalSource<T> =
-  AsyncIterator<T> & { _destination: AsyncIterator<any> };
+  AsyncIterator<T> & { _destination?: AsyncIterator<any> };

Original file line number	Diff line number	Diff line change
`@@ -1241,7 +1241,7 @@ export class TransformIterator<S, D = S> extends BufferedIterator<D> {`
`1241`	`1241`	`}`
`1242`	`1242`
`1243`	`1243`	`function destinationEmitError<S>(this: InternalSource<S>, error: Error) {`
`1244`		`- this._destination.emit('error', error);`
	`1244`	`+ this._destination!.emit('error', error);`
`1245`	`1245`	`}`
`1246`	`1246`	`function destinationCloseWhenDone<S>(this: InternalSource<S>) {`
`1247`	`1247`	`(this._destination as any)._closeWhenDone();`
`@@ -1985,4 +1985,4 @@ type SourceExpression<T> =`
`1985`	`1985`	`(() => MaybePromise<AsyncIterator<T>>);`
`1986`	`1986`
`1987`	`1987`	`type InternalSource<T> =`
`1988`		`- AsyncIterator<T> & { _destination: AsyncIterator<any> };`
	`1988`	`+ AsyncIterator<T> & { _destination?: AsyncIterator<any> };`