To Reproduce
Steps to reproduce the behavior:

1. Disable code_block and code_fence extensions
2. Open an existing document (value) in editor that has a line starting with 4 consecutive spaces (" ")
3. Editor will crash
4. See error

Expected behavior
Should not crash. Should probably handle trailing spaces beginning of newline as nothing.

I am simply opening an editor with value I created in editor.

Console Sample:
Error: Token type code_block not supported by Markdown parser
at MarkdownParseState.parseTokens (from_markdown.js:55)
at MarkdownParser.parse (from_markdown.js:219)
at RichMarkdownEditor.createDocument (index.tsx:485)
at RichMarkdownEditor.createState (index.tsx:466)
at RichMarkdownEditor.createView (index.tsx:502)
at RichMarkdownEditor.init (index.tsx:290)
at RichMarkdownEditor.componentDidMount (index.tsx:208)
at commitLifeCycles (react-dom.development.js:20663)
at commitLayoutEffects (react-dom.development.js:23426)
at HTMLUnknownElement.callCallback (react-dom.development.js:3945)
at Object.invokeGuardedCallbackDev (react-dom.development.js:3994)
at invokeGuardedCallback (react-dom.development.js:4056)
at commitRootImpl (react-dom.development.js:23151)
at unstable_runWithPriority (scheduler.development.js:468)
at runWithPriority$1 (react-dom.development.js:11276)
at commitRoot (react-dom.development.js:22990)
at performSyncWorkOnRoot (react-dom.development.js:22329)
at react-dom.development.js:11327
at unstable_runWithPriority (scheduler.development.js:468)
at runWithPriority$1 (react-dom.development.js:11276)
at flushSyncCallbackQueueImpl (react-dom.development.js:11322)
at flushSyncCallbackQueue (react-dom.development.js:11309)
at batchedUpdates$1 (react-dom.development.js:22387)
at reactionScheduler (reaction.ts:261)
at runReactions (reaction.ts:229)
at endBatch (observable.ts:111)
at _endAction (action.ts:138)
at executeAction (action.ts:70)
at bound openMyTasksPage (action.ts:46)
at runMiddleWares (mobx-state-tree.module.js:3234)
at runWithActionContext (mobx-state-tree.module.js:3078)
at Proxy.res (mobx-state-tree.module.js:3105)
at NewTaskStore.js:80

Similar Error message for code_fence, when multiple places with 4 trailing spaces (in middle of line).