Add error warning to MessageService

Stronger then warning.

projects/common/message.service.ts

@@ -10,4 +10,8 @@ export class MessageService {
   showWarning(text: string): void {
     this._snackBar.open(text, undefined, { duration: 2000, panelClass: 'snackbar-warning' });
   }
+
+  showError(text: string): void {
+    this._snackBar.open(text, undefined, { duration: 2000, panelClass: 'snackbar-error' });
+  }
 }

projects/editor/src/styles.css

@@ -6,3 +6,4 @@ body {
 }
 
 .snackbar-warning {border: 3px double #ff4d4d}
+.snackbar-error {background-color: #ff4d4d}