Make the AS pending transaction promise propagate errors

src/appservice/Appservice.ts

@@ -236,7 +236,7 @@ export class Appservice extends EventEmitter {
     private appServer: any;
     private intentsCache: LRU.LRUCache<string, Intent>;
     private eventProcessors: { [eventType: string]: IPreprocessor[] } = {};
-    private pendingTransactions: { [txnId: string]: Promise<any> } = {};
+    private pendingTransactions: { [txnId: string]: Promise<void> } = {};
 
     /**
      * Creates a new application service.
@@ -695,8 +695,7 @@ export class Appservice extends EventEmitter {
         }
 
         LogService.info("Appservice", "Processing transaction " + txnId);
-        // eslint-disable-next-line no-async-promise-executor
-        this.pendingTransactions[txnId] = new Promise<void>(async (resolve) => {
+        this.pendingTransactions[txnId] = Promise.resolve((async () => {
             // Process all the crypto stuff first to ensure that future transactions (if not this one)
             // will decrypt successfully. We start with EDUs because we need structures to put counts
             // and such into in a later stage, and EDUs are independent of crypto.
@@ -891,9 +890,7 @@ export class Appservice extends EventEmitter {
                     this.emit("room.upgraded", event['room_id'], event);
                 }
             }
-
-            resolve();
-        });
+        })());
 
         try {
             await this.pendingTransactions[txnId];