[gtk] Avoid a crash without librsvg

[Matthias Clasen <matthiasc src gnome org>]

commit 69f12ed6a5f48b90c1060d76764307c1d5167197
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Apr 18 00:08:16 2019 +0000

    Avoid a crash without librsvg
    
    gtk_css_image_recolor_load_texture may leave
    recolor->text as NULL without setting error.
    No need to crash for that.

 gtk/gtkcssimagerecolor.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtkcssimagerecolor.c b/gtk/gtkcssimagerecolor.c
index d4e0bd3d3c..7dadd660a0 100644
--- a/gtk/gtkcssimagerecolor.c
+++ b/gtk/gtkcssimagerecolor.c
@@ -157,7 +157,7 @@ gtk_css_image_recolor_load (GtkCssImageRecolor  *recolor,
           g_set_error (gerror,
                        GTK_CSS_PARSER_ERROR,
                        GTK_CSS_PARSER_ERROR_FAILED,
-                       "Error loading image '%s': %s", uri, local_error->message);
+                       "Error loading image '%s': %s", uri, local_error ? local_error->message : "");
           g_free (uri);
        }
     }