Remove errors from the cache when they are shown to the user (#1392)

There's really no reason to retry encryption errors again if they've
already been made user-visible in a conversation.

Also, refactor e->error in background.js onError(), since both e and ev
in this method made it too easy to make a mistake.

js/background.js

@@ -302,18 +302,18 @@
     }
 
     function onError(ev) {
-        var e = ev.error;
-        console.log(e);
-        console.log(e.stack);
+        var error = ev.error;
+        console.log(error);
+        console.log(error.stack);
 
-        if (e.name === 'HTTPError' && (e.code == 401 || e.code == 403)) {
+        if (error.name === 'HTTPError' && (error.code == 401 || error.code == 403)) {
             Whisper.Registration.remove();
             Whisper.events.trigger('unauthorized');
             extension.install();
             return;
         }
 
-        if (e.name === 'HTTPError' && e.code == -1) {
+        if (error.name === 'HTTPError' && error.code == -1) {
             // Failed to connect to server
             if (navigator.onLine) {
                 console.log('retrying in 1 minute');
@@ -329,7 +329,10 @@
         }
 
         if (ev.proto) {
-            if (e.name === 'MessageCounterError') {
+            if (error.name === 'MessageCounterError') {
+                if (ev.confirm) {
+                    ev.confirm();
+                }
                 // Ignore this message. It is likely a duplicate delivery
                 // because the server lost our ack the first time.
                 return;
@@ -337,7 +340,7 @@
             var envelope = ev.proto;
             var message = initIncomingMessage(envelope);
 
-            return message.saveErrors(e).then(function() {
+            return message.saveErrors(error).then(function() {
                 var id = message.get('conversationId');
                 return ConversationController.findOrCreateById(id, 'private').then(function(conversation) {
                     conversation.set({
@@ -356,6 +359,10 @@
                         conversation.notify(message);
                     }
 
+                    if (ev.confirm) {
+                        ev.confirm();
+                    }
+
                     return new Promise(function(resolve, reject) {
                         conversation.save().then(resolve, reject);
                     });
@@ -363,7 +370,7 @@
             });
         }
 
-        throw e;
+        throw error;
     }
 
     function onReadReceipt(ev) {

js/libtextsecure.js

@@ -38631,6 +38631,7 @@ MessageReceiver.prototype.extend({
             var ev = new Event('error');
             ev.error = error;
             ev.proto = envelope;
+            ev.confirm = this.removeFromCache.bind(this, envelope);
 
             var returnError = function() {
                 return Promise.reject(error);

libtextsecure/message_receiver.js

@@ -380,6 +380,7 @@ MessageReceiver.prototype.extend({
             var ev = new Event('error');
             ev.error = error;
             ev.proto = envelope;
+            ev.confirm = this.removeFromCache.bind(this, envelope);
 
             var returnError = function() {
                 return Promise.reject(error);