Fix 3D scene preview generation.

File system dock previews will now be generated for 3D scenes when no
editor feature profile is set.

editor/editor_node.cpp

@@ -1408,8 +1408,9 @@ void EditorNode::_save_scene_with_preview(String p_file, int p_idx) {
 		} else {
 			// The 3D editor may be disabled as a feature, but scenes can still be opened.
 			// This check prevents the preview from regenerating in case those scenes are then saved.
+			// The preview will be generated if no feature profile is set (as the 3D editor is enabled by default).
 			Ref<EditorFeatureProfile> profile = feature_profile_manager->get_current_profile();
-			if (profile.is_valid() && !profile->is_feature_disabled(EditorFeatureProfile::FEATURE_3D)) {
+			if (!profile.is_valid() || !profile->is_feature_disabled(EditorFeatureProfile::FEATURE_3D)) {
 				img = Node3DEditor::get_singleton()->get_editor_viewport(0)->get_viewport_node()->get_texture()->get_image();
 			}
 		}