Cleanup closed connection when client disconnects. (#5783)

Fixes #5346

(Thank you @beezital)

Author: taeold

CHANGELOG.md

@@ -10,3 +10,4 @@
 - Fixes bug where the functions emulator would attempt to call to prod for 'demo-' projects (#5170)
 - Address issues starting the Firebase Hosting emulator with some versions of Next.js (#5781)
 - Fix regex page matcher for Next.js middlewares version 1 (#5496)
+- Fixes bug where functions emulator broke when client request disconnects (#5783)

src/emulator/functionsRuntimeWorker.ts

@@ -161,11 +161,20 @@ export class RuntimeWorker {
       }
       const proxy = http.request(reqOpts, (_resp: http.IncomingMessage) => {
         resp.writeHead(_resp.statusCode || 200, _resp.headers);
+
+        let finished = false;
+        const finishReq = (event?: string): void => {
+          this.logger.log("DEBUG", `Finishing up request with event=${event}`);
+          if (!finished) {
+            finished = true;
+            onFinish();
+            resolve();
+          }
+        };
+        _resp.on("pause", () => finishReq("pause"));
+        _resp.on("close", () => finishReq("close"));
         const piped = _resp.pipe(resp);
-        piped.on("finish", () => {
-          onFinish();
-          resolve();
-        });
+        piped.on("finish", () => finishReq("finish"));
       });
       proxy.on("timeout", () => {
         this.logger.log(