[gnome-builder/wip/gtk4-port] libide/gui: handle NULL as request to clear loading CSS

[Christian Hergert <chergert src gnome org>]

commit e9ff075a2ef4d02f304aac5d7195fb01833fadf3
Author: Christian Hergert <chergert redhat com>
Date:   Thu Mar 31 14:44:09 2022 -0700

    libide/gui: handle NULL as request to clear loading CSS

 src/libide/gui/ide-application-color.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/libide/gui/ide-application-color.c b/src/libide/gui/ide-application-color.c
index 94161065e..6cbe322ba 100644
--- a/src/libide/gui/ide-application-color.c
+++ b/src/libide/gui/ide-application-color.c
@@ -176,8 +176,8 @@ ide_application_color_style_scheme_changed_cb (IdeApplication *self,
   if (scheme == NULL)
     return;
 
-  if ((css = _ide_recoloring_generate_css (scheme)))
-    gtk_css_provider_load_from_data (self->recoloring, css, -1);
+  css = _ide_recoloring_generate_css (scheme);
+  gtk_css_provider_load_from_data (self->recoloring, css ? css : "", -1);
 }
 
 void