Fix #124647: UV editing console error due to missing enum

IMAGE_AST_brush_paint poll should check context.space_data.mode
rather than context.space_data.ui_mode.

Pull Request: https://projects.blender.org/blender/blender/pulls/124762

scripts/startup/bl_ui/space_image.py

@@ -1706,7 +1706,7 @@ class IMAGE_AST_brush_paint(ImageAssetShelf, AssetShelf):
 
     @classmethod
     def poll(cls, context):
-        return context.space_data and context.space_data.ui_mode == 'PAINT'
+        return context.space_data and context.space_data.mode == 'PAINT'
 
 
 classes = (