For macOS app, add catch for JS error, displayign a dialog to the user.

Its a start of handling this a little better - but hopefully the user never sees this...

Author: wcjohns

src/InterSpecApp.cpp

@@ -514,14 +514,27 @@ void InterSpecApp::setupWidgets( const bool attemptStateLoad  )
     delete m_viewer;
     m_viewer = nullptr;
   }
-  
+
   if( m_layout )
   {
     delete m_layout;
     root()->clear();
   }
-  
-  
+
+
+#if( BUILD_AS_OSX_APP )
+  // Inject JavaScript to catch errors, that the objective-c will then recieve.
+  const string jsErrorCode = "window.onerror = function(message, source, lineno, colno, error) {\n"
+  "  console.error( 'JS Error:', message, ', from source:', source, ', lineno:', lineno, ', error:', error );\n"
+  "  window.webkit.messageHandlers.jsErrorHandler.postMessage({\n"
+  "    message: message, source: source, lineno: lineno, colno: colno, error: error ? error.toString() : null\n"
+  "  });\n"
+  "};";
+
+  doJavaScript( jsErrorCode );
+#endif // #if( BUILD_AS_OSX_APP )
+
+
   try
   {
     m_viewer = new InterSpec();

target/osx/AppDelegate.mm

@@ -429,7 +429,10 @@ - (void)applicationDidFinishLaunching:(NSNotification *)aNotification
   //  does something like:
   //      window.webkit.messageHandlers.interOp.postMessage({"action": "DoSomething"});
   [webConfig.userContentController addScriptMessageHandler: self name:@"interOp"];
-  
+
+  // Add a script message handler
+  [webConfig.userContentController addScriptMessageHandler:self name:@"jsErrorHandler"];
+
   //Some additional settings we may want to set:
   //  see more at http://jonathanblog2000.blogspot.com/2016/11/understanding-ios-wkwebview.html
   //[prefs setValue:@YES forKey:@"allowFileAccessFromFileURLs"];
@@ -1179,16 +1182,41 @@ - (void)applicationWillTerminate:(NSNotification *)notification
 // This method is for WKScriptMessageHandler, and is triggered each time 'interOp' is sent a
 //    message from the JavaScript code with something like:
 //      window.webkit.messageHandlers.interOp.postMessage({"val": 1});
+//      window.webkit.messageHandlers.jsErrorHandler.postMessage({"message": message, "source": source, ...} );
 - (void)userContentController:(WKUserContentController *)userContentController
       didReceiveScriptMessage:(WKScriptMessage *)message{
   NSDictionary *sentData = (NSDictionary*)message.body;
-  
+
   if( sentData == nil )
   {
     NSLog( @"didReceiveScriptMessage: got nil dictionary" );
     return;
   }
-  
+
+  if ([message.name isEqualToString:@"jsErrorHandler"]) {
+    NSString *errorMessage = sentData[@"message"];
+    NSString *source = sentData[@"source"];
+    NSNumber *lineNumber = sentData[@"lineno"];
+    NSNumber *columnNumber = sentData[@"colno"];
+    NSString *errorDetails = sentData[@"error"];
+
+    // Create the alert
+    NSAlert *alert = [[NSAlert alloc] init];
+    alert.messageText = @"JavaScript Error";
+    alert.informativeText = [NSString stringWithFormat:@"Unexpected JavaScript Error - please consider reporting to [email protected] and restarting app:\n\nMessage: %@\nSource: %@\nLine: %@\nColumn: %@\nDetails: %@",
+       errorMessage ?: @"Unknown",
+       source ?: @"Unknown",
+       lineNumber ?: @0,
+       columnNumber ?: @0,
+       errorDetails ?: @"No additional details"];
+    alert.alertStyle = NSAlertStyleWarning;
+
+    [alert addButtonWithTitle:@"OK"];
+    [alert runModal];
+
+    return;
+  }//if( a JS error )
+
   id val = [sentData objectForKey: @"action"];
   if( val != (id)[NSNull null] )
   {