Make HTTPServer ignore responses that cannot be sent

src/http/lifecycle/Response.ts

@@ -255,6 +255,14 @@ export class Response {
         await this.sent$.next(this)
     }
 
+    /**
+     * Returns true if the response can still be sent. False if it has been sent
+     * or the connection has been destroyed.
+     */
+    public canSend(): boolean {
+        return !(this.responseEnded || this.serverResponse.destroyed)
+    }
+
     /**
      * Mark the response as ended and close the socket.
      */

src/service/HTTPServer.ts

@@ -128,7 +128,9 @@ export class HTTPServer extends Unit {
                     await error(new ErrorWithContext('Unknown error occurred.', { e }))
                 }
 
-                await extolloReq.response.send()
+                if ( extolloReq.response.canSend() ) {
+                    await extolloReq.response.send()
+                }
             })
         }
     }