extensions-tool: Log existing errors

In many cases we currently only indicate failure in the return value,
which is easily missed. Print some meaningful errors instead.

https://gitlab.gnome.org/GNOME/gnome-shell/issues/2391

subprojects/extensions-tool/src/command-uninstall.c

@@ -45,10 +45,16 @@ uninstall_extension (const char *uuid)
                                      NULL,
                                      &error);
   if (response == NULL)
-    return FALSE;
+    {
+      g_printerr (_("Failed to connect to GNOME Shell"));
+      return FALSE;
+    }
 
   g_variant_get (response, "(b)", &success);
 
+  if (!success)
+    g_printerr (_("Failed to uninstall “%s”\n"), uuid);
+
   return success;
 }