[gimp] app: better error management.

[Jehan <jehanp src gnome org>]

commit 8528759834a694cfbf09fd38bdf8fe5bc5feeff7
Author: Jehan <jehan girinstud io>
Date:   Sun Jan 26 15:10:44 2020 +0100

    app: better error management.
    
    - Clear the GError when relevant.
    - Check result of json_path_compile() just in case.
    - Print some error on stderr when parsing of gimp_versions.json fails
      (which should never happen on releases but would help during
      development).

 app/gimp-update.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)
---
diff --git a/app/gimp-update.c b/app/gimp-update.c
index 966b3dc0d9..bfe84dbd79 100644
--- a/app/gimp-update.c
+++ b/app/gimp-update.c
@@ -112,8 +112,13 @@ gimp_check_updates_callback (GObject      *source,
       parser = json_parser_new ();
       if (! json_parser_load_from_stream (parser, G_INPUT_STREAM (stream), NULL, &error))
         {
+#ifdef GIMP_UNSTABLE
+          g_printerr("Parsing of %s failed: %s\n",
+                     g_file_get_uri (G_FILE (source)), error->message);
+#endif
           g_clear_object (&stream);
           g_clear_object (&parser);
+          g_clear_error (&error);
 
           return;
         }
@@ -128,7 +133,17 @@ gimp_check_updates_callback (GObject      *source,
        * Unfortunately json-glib does not support filter syntax, so we
        * end up looping through releases.
        */
-      json_path_compile (path, "$['STABLE'][*]", &error);
+      if (! json_path_compile (path, "$['STABLE'][*]", &error))
+        {
+#ifdef GIMP_UNSTABLE
+          g_printerr("Path compilation failed: %s\n", error->message);
+#endif
+          g_clear_object (&stream);
+          g_clear_object (&parser);
+          g_clear_error (&error);
+
+          return;
+        }
       result = json_path_match (path, json_parser_get_root (parser));
       g_return_if_fail (JSON_NODE_HOLDS_ARRAY (result));