fix: use a short-lived AbortSignal for fetch operations (#511)

Node's `undici` module appears to be adding listeners for the `"abort"` event on any passed AbortSignal but then not cleaning them up.

This casues many `MaxListenersExceededWarning`s to appear in the console and likely causes a memory leak.

To work around this, use a short-lived `AbortSignal` for each request that can be garbage collected along with the request itself.

See https://github.com/nodejs/node/issues/52635 for more information.

packages/block-brokers/src/trustless-gateway/trustless-gateway.ts

@@ -91,12 +91,20 @@ export class TrustlessGateway {
  }
 
  const blockId = this.#uniqueBlockId(cid)
+
+ // workaround for https://github.com/nodejs/node/issues/52635
+ const innerController = new AbortController()
+ const abortInnerSignal = (): void => {
+ innerController.abort()
+ }
+ signal?.addEventListener('abort', abortInnerSignal)
+
  try {
  let pendingResponse: Promise<Uint8Array> | undefined = this.#pendingResponses.get(blockId)
  if (pendingResponse == null) {
  this.#attempts++
  pendingResponse = fetch(gwUrl.toString(), {
- signal,
+ signal: innerController.signal,
  headers: {
  Accept: 'application/vnd.ipld.raw'
  },
@@ -122,6 +130,7 @@ export class TrustlessGateway {
  this.#errors++
  throw new Error(`unable to fetch raw block for CID ${cid}`)
  } finally {
+ signal?.removeEventListener('abort', abortInnerSignal)
  this.#pendingResponses.delete(blockId)
  }
  }