[gnome-shell] extensionSystem: Unload stylesheet if extension is not loaded

[Marco Trevisan <marcotrevi src gnome org>]

commit 3aea290adcbf7d12e6d8ec8230afbd8c3cb74606
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Fri Aug 3 17:52:19 2018 +0200

    extensionSystem: Unload stylesheet if extension is not loaded
    
    We should not keep any reference to an extension custom stylesheet in case we
    got an error while enabling that

 js/ui/extensionSystem.js | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/js/ui/extensionSystem.js b/js/ui/extensionSystem.js
index 3f23d273e..6611b5a63 100644
--- a/js/ui/extensionSystem.js
+++ b/js/ui/extensionSystem.js
@@ -136,6 +136,10 @@ function enableExtension(uuid) {
         _signals.emit('extension-state-changed', extension);
         return;
     } catch(e) {
+        if (extension.stylesheet) {
+            theme.unload_stylesheet(extension.stylesheet);
+            delete extension.stylesheet;
+        }
         logExtensionError(uuid, e);
         return;
     }