Improve error display cross-browsers, and add translatable string

client/src/components/Draftail/EditorFallback/EditorFallback.js

@@ -83,7 +83,7 @@ class EditorFallback extends PureComponent {
             className="Draftail-ToolbarButton"
             onClick={this.toggleError}
           >
-            {'Show error'}
+            {STRINGS.SHOW_ERROR}
           </button>
 
           {/* At first we propose reloading the editor. If it still crashes, reload the whole page. */}
@@ -122,7 +122,7 @@ class EditorFallback extends PureComponent {
               {showError && (
                 <pre className="help-block help-critical">
                   <code className="EditorFallback__error">
-                    {`${error.stack}\n${info.componentStack}`}
+                    {`${error.name}: ${error.message}\n\n${error.stack}\n${info.componentStack}`}
                   </code>
                 </pre>
               )}

client/src/components/Draftail/EditorFallback/__snapshots__/EditorFallback.test.js.snap

@@ -88,7 +88,9 @@ exports[`EditorFallback #error #showError 1`] = `
           <code
             className="EditorFallback__error"
           >
-            test stack
+            Error: test
+
+test stack
 test
           </code>
         </pre>

client/tests/stubs.js

@@ -39,6 +39,7 @@ global.wagtailConfig = {
     RELOAD_PAGE: 'Reload the page',
     RELOAD_EDITOR: 'Reload saved content',
     SHOW_LATEST_CONTENT: 'Show latest content',
+    SHOW_ERROR: 'Show error',
     EDITOR_CRASH: 'The editor just crashed. Content has been reset to the last saved version.',
   },
 };

wagtail/admin/templates/wagtailadmin/admin_base.html

@@ -47,6 +47,7 @@
                 RELOAD_PAGE: "{% trans 'Reload the page' %}",
                 RELOAD_EDITOR: "{% trans 'Reload saved content' %}",
                 SHOW_LATEST_CONTENT: "{% trans 'Show latest content' %}",
+                SHOW_ERROR: "{% trans 'Show error' %}",
                 EDITOR_CRASH: "{% trans 'The editor just crashed. Content has been reset to the last saved version.' %}",
             };