Respond to malformed messages with empty body

ts/textsecure/MessageReceiver.ts

@@ -407,6 +407,7 @@ export default class MessageReceiver
     }
 
     const job = async () => {
+      try {
         if (!request.body) {
           throw new Error(
             'MessageReceiver.handleRequest: request.body was falsey!'
@@ -415,7 +416,6 @@ export default class MessageReceiver
 
         const plaintext = request.body;
 
-      try {
         const decoded = Proto.Envelope.decode(plaintext);
         const serverTimestamp = decoded.serverTimestamp?.toNumber() ?? 0;