add a less intimidating error message when backend times out and/or fails to return valid JSON

js/functions.js

@@ -833,7 +833,7 @@ function quickAddFeed() {
 									var reply = JSON.parse(transport.responseText);
 								} catch (e) {
 									Element.hide("feed_add_spinner");
-									alert(__("Failed to parse output. This can indicate server timeout and/or network issues. Backend output was logged to browser console."));
+									alert(__("Failed to parse output. This can indicate server timeout and/or network issues. Backend output was logged to the browser console."));
 									console.log('quickAddFeed, backend returned:' + transport.responseText);
 									return;
 								}

js/tt-rss.js

@@ -987,7 +987,12 @@ function newVersionDlg() {
 
 function handle_rpc_json(transport, scheduled_call) {
 	try {
-		var reply = JSON.parse(transport.responseText);
+		try {
+			var reply = JSON.parse(transport.responseText);
+		} catch (e) {
+			alert(__("Failed to parse server reply. This could be caused by a server or network timeout. Backend output was logged to the browser console."));
+			console.log("handle_rpc_json, received: " + transport.responseText);
+		}
 
 		if (reply) {