If first action upon loading editor is checking a list item, error is thrown

[wrobbinz]

Description
Given an initial editor state contains a checkable-list-item, and no action has been taken on the editor (i.e. refreshed page), toggling a checkbox in the editor will throw a console error.

Steps to Reproduce

1. Set up minimal draftjs editor with markdown plugin.
2. Provide an initial state that contains a checkbox
3. Before any other action, check/uncheck the box

Expected
Checkbox is toggled and no error is thrown.

Actual Result
Checkbox is checked/unchecked and an error is thrown. There may be a slight delay when checking the box (minor if so)

Uncaught TypeError: Cannot read property 'nodeType' of null
    at editOnInput (editOnInput.js:52)
    at DraftEditor.react.js:216
    at HTMLUnknownElement.callCallback (react-dom.development.js:100)
    at Object.invokeGuardedCallbackDev (react-dom.development.js:138)
    at Object.invokeGuardedCallback (react-dom.development.js:187)
    at Object.invokeGuardedCallbackAndCatchFirstError (react-dom.development.js:201)
    at executeDispatch (react-dom.development.js:461)
    at executeDispatchesInOrder (react-dom.development.js:483)
    at executeDispatchesAndRelease (react-dom.development.js:581)
    at executeDispatchesAndReleaseTopLevel (react-dom.development.js:592)
    at forEachAccumulated (react-dom.development.js:562)
    at runEventsInBatch (react-dom.development.js:723)
    at runExtractedEventsInBatch (react-dom.development.js:732)
    at handleTopLevel (react-dom.development.js:4472)
    at batchedUpdates$1 (react-dom.development.js:16537)
    at batchedUpdates (react-dom.development.js:2131)
    at dispatchEvent (react-dom.development.js:4551)
    at interactiveUpdates$1 (react-dom.development.js:16592)
    at interactiveUpdates (react-dom.development.js:2150)
    at dispatchInteractiveEvent (react-dom.development.js:4528)

[juliankrispel]

I can't reproduce this particular error - in fact checkable list items don't work at all for me (when loaded from raw content state), could you please provide an example via codesandbox so we can reproduce your bug?