fix open_tab() not returning false on failure

ext/bg.js

@@ -241,11 +241,25 @@ function attach_ws_events(ws){
 				break;
 			
 			case "tab_open":
-				var tab =
-					await browser.tabs.create({
-						url: msg.url,
-						...(typeof msg.container == "string" && { cookieStoreId: msg.container })
+				
+				// sometimes opening tabs like about:blank with a
+				// container will fail.
+				var tab = null;
+				
+				try{
+					tab =
+						await browser.tabs.create({
+							url: msg.url,
+							...(typeof msg.container == "string" && { cookieStoreId: msg.container })
+						});
+				}catch(err){
+					
+					// send error: we attempted to open tab
+					send(ws, seqid, {
+						data: false
 					});
+					break;
+				}
 				
 				// immediately return even if its not loaded yet
 				send(ws, seqid, {