[gnome-software] trivial: Don't print a warning about empty error messages

[Richard Hughes <rhughes src gnome org>]

commit 1d1fb725be8f8577ec0b39cde58e7179f6f6e23e
Author: Richard Hughes <richard hughsie com>
Date:   Mon Jun 13 10:45:06 2016 +0100

    trivial: Don't print a warning about empty error messages

 src/plugins/gs-plugin-shell-extensions.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/plugins/gs-plugin-shell-extensions.c b/src/plugins/gs-plugin-shell-extensions.c
index c1ec33d..a97561d 100644
--- a/src/plugins/gs-plugin-shell-extensions.c
+++ b/src/plugins/gs-plugin-shell-extensions.c
@@ -243,7 +243,7 @@ gs_plugin_shell_extensions_changed_cb (GDBusProxy *proxy,
                gs_app_set_state (app, st);
 
                /* not sure what to do here */
-               if (error_str != NULL) {
+               if (error_str != NULL && error_str[0] != '\0') {
                        g_warning ("%s has error: %s",
                                   gs_app_get_id (app),
                                   error_str);