Cancel drawing operation when layer is locked/hidden (similar to GPv2). Otherwise `get_editable_drawing_at` returns nullptr which results in crash and assert hit. Pull Request: https://projects.blender.org/blender/blender/pulls/116779
Cancel drawing operation when layer is locked/hidden (similar to GPv2). Otherwise `get_editable_drawing_at` returns nullptr which results in crash and assert hit. Pull Request: https://projects.blender.org/blender/blender/pulls/116779