Uncaught TypeError: Cannot read property 'getGrammar' of undefined

[BoobooWei]

[Enter steps to reproduce:]

1. ...
2. ...

Atom: 1.48.0-beta0 x64
Electron: 5.0.13
OS: Mac OS X 10.14.3
Thrown From: tidy-markdown package 3.0.1

Stack Trace

Uncaught TypeError: Cannot read property 'getGrammar' of undefined

At /Users/booboowei/.atom/packages/tidy-markdown/lib/index.coffee:37

TypeError: Cannot read property 'getGrammar' of undefined
    at TidyMarkdown.run (/packages/tidy-markdown/lib/index.coffee:37:15)
    at /packages/tidy-markdown/lib/index.coffee:11:32)
    at CommandRegistry.handleCommandEvent (/Applications/Atom Beta.app/Contents/Resources/app/static/<embedded>:11:349786)
    at CommandRegistry.dispatch (/Applications/Atom Beta.app/Contents/Resources/app/static/<embedded>:11:348261)
    at AtomEnvironment.dispatchApplicationMenuCommand (/Applications/Atom Beta.app/Contents/Resources/app/static/<embedded>:1:725974)
    at EventEmitter.t (/Applications/Atom Beta.app/Contents/Resources/app/static/<embedded>:1:733897)
    at EventEmitter.emit (events.js:194:13)

Commands

  2x -6:42.8.0 window:install-shell-commands (input.hidden-input)
     -3:16.6.0 core:backspace (input.hidden-input)
     -3:15.1.0 core:confirm (input.hidden-input)
     -0:39.7.0 markdown-preview:toggle-github-style (input.hidden-input)
     -0:29.5.0 markdown-preview:toggle (input.hidden-input)
     -0:10.6.0 tidy-markdown:run (div.markdown-preview)

Non-Core Packages

atom-mdtoc 0.8.4 
language-tick 0.4.0 
markdown-preview-enhanced 0.18.2 
markdown-toc-auto 0.14.0 
tidy-markdown 3.0.1