[gnome-shell] extensionSystem: Don't log error name

[Florian Müllner <fmuellner src gnome org>]

commit 48e6a58250fd0f59acbed48ee5c222b459c875d8
Author: Florian Müllner <fmuellner gnome org>
Date:   Tue May 12 01:12:50 2020 +0200

    extensionSystem: Don't log error name
    
    logExtensionError() currently saves the error message by calling
    toString() on the passed error. That's convenient as it allows to
    pass a string instead of a "proper" error, but the result isn't
    great for the common Error case: Its toString() method prefixes
    the message with the error name, which usually is just "Error:".
    
    The plain message is more suitable for displaying it to users,
    so use that for Error objects.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/2337

 js/ui/extensionSystem.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/js/ui/extensionSystem.js b/js/ui/extensionSystem.js
index 50244d95fc..f0b8361714 100644
--- a/js/ui/extensionSystem.js
+++ b/js/ui/extensionSystem.js
@@ -260,7 +260,8 @@ var ExtensionManager = class {
         if (!extension)
             return;
 
-        let message = error.toString();
+        const message = error instanceof Error
+            ? error.message : error.toString();
 
         extension.error = message;
         extension.state = ExtensionState.ERROR;