The insertion marker manager tried to create a marker but the result is missing a field.

[m lz]

hi,I try to write an text_print block with mutiple input with mutator,and I check the plus-minus plugin code write a demo with codepen.io

https://codepen.io/mlzboy/pen/OJaqJqE?editors=1011

after I finished the demo there is something wrong if I drag the block, it will throw an error

insertion_marker_manager.ts:273 Uncaught Error: The insertion marker manager tried to create a marker but the result is missing a field. If you are using a mutator, make sure your domToMutation method is properly defined.
    at InsertionMarkerManager$$module$build$src$core$insertion_marker_manager.createMarkerBlock (insertion_marker_manager.ts:273)
    at new InsertionMarkerManager$$module$build$src$core$insertion_marker_manager (insertion_marker_manager.ts:135)
    at new BlockDragger$$module$build$src$core$block_dragger (block_dragger.ts:65)
    at Gesture$$module$build$src$core$gesture.startDraggingBlock_ (gesture.ts:417)
    at Gesture$$module$build$src$core$gesture.updateIsDraggingBlock_ (gesture.ts:353)
    at Gesture$$module$build$src$core$gesture.updateIsDragging_ (gesture.ts:404)
    at Gesture$$module$build$src$core$gesture.updateFromEvent_ (gesture.ts:243)
    at Gesture$$module$build$src$core$gesture.handleMove (gesture.ts:557)
    at HTMLDocument.g (browser_events.ts:78)

bellow is my screenshot

https://cloud-minapp-33002.cloud.ifanrusercontent.com/1qRh9vKLMU5yafvL.png