Uncaught TypeError: Cannot read property 'then' of undefined

[francknouama]

[Enter steps to reproduce below:]

1. ...
2. ...

Atom Version: 1.0.19
System: Mac OS X 10.10.5
Thrown From: dart-tools package, v0.9.23

Stack Trace

Uncaught TypeError: Cannot read property 'then' of undefined

At /Applications/Atom.app/Contents/Resources/app.asar/src/pane.js:809

TypeError: Cannot read property 'then' of undefined
  at Formatter.module.exports.Formatter.formatEditor (/Users/francknouama/.atom/packages/dart-tools/lib/formatter.coffee:66:19)
  at Formatter.formatEditor (/Users/francknouama/.atom/packages/dart-tools/lib/formatter.coffee:1:1)
  at /Users/francknouama/.atom/packages/dart-tools/lib/formatter.coffee:84:8
  at Emitter.module.exports.Emitter.emit (/Applications/Atom.app/Contents/Resources/app.asar/node_modules/event-kit/lib/emitter.js:82:11)
  at TextBuffer.module.exports.TextBuffer.saveAs (/Applications/Atom.app/Contents/Resources/app.asar/node_modules/text-buffer/lib/text-buffer.js:1037:20)
  at TextBuffer.module.exports.TextBuffer.save (/Applications/Atom.app/Contents/Resources/app.asar/node_modules/text-buffer/lib/text-buffer.js:1004:19)
  at TextEditor.module.exports.TextEditor.save (/Applications/Atom.app/Contents/Resources/app.asar/src/text-editor.js:584:26)
  at Pane.module.exports.Pane.saveItem (/Applications/Atom.app/Contents/Resources/app.asar/src/pane.js:547:18)
  at Pane.module.exports.Pane.saveActiveItem (/Applications/Atom.app/Contents/Resources/app.asar/src/pane.js:530:19)
  at Workspace.module.exports.Workspace.saveActivePaneItem (/Applications/Atom.app/Contents/Resources/app.asar/src/workspace.js:609:35)
  at atom-workspace.atom.commands.add.core:save (/Applications/Atom.app/Contents/Resources/app.asar/src/workspace-element.js:293:30)
  at CommandRegistry.module.exports.CommandRegistry.handleCommandEvent (/Applications/Atom.app/Contents/Resources/app.asar/src/command-registry.js:245:29)
  at /Applications/Atom.app/Contents/Resources/app.asar/src/command-registry.js:3:61
  at KeymapManager.module.exports.KeymapManager.dispatchCommandEvent (/Applications/Atom.app/Contents/Resources/app.asar/node_modules/atom-keymap/lib/keymap-manager.js:524:16)
  at KeymapManager.module.exports.KeymapManager.handleKeyboardEvent (/Applications/Atom.app/Contents/Resources/app.asar/node_modules/atom-keymap/lib/keymap-manager.js:347:22)
  at HTMLDocument.module.exports.WindowEventHandler.onKeydown (/Applications/Atom.app/Contents/Resources/app.asar/src/window-event-handler.js:184:20)

Commands

     -4:57.8.0 dartlang:getting-started (div.settings-view.pane-item)
  4x -2:26.6.0 core:backspace (atom-text-editor.editor.mini.is-focused)
  2x -2:17.7.0 core:confirm (atom-text-editor.editor.mini.is-focused)
     -0:02.0 core:save (atom-text-editor.editor.is-focused)

Config

{
  "core": {
    "themes": [
      "atom-dark-ui",
      "atom-dark-syntax"
    ],
    "followSymlinks": false
  }
}

Installed Packages

# User
Package-Upgrader, v0.3.1
atom-beautify, v0.28.14
auto-update-packages, v1.0.0
autoclose-html, v0.19.0
autocomplete-html-entities, v0.1.0
autocomplete-polymer, v0.2.4
autocomplete-sass, v0.1.0
case-switch, v0.5.0
dart-tools, v0.9.23
dartlang, v0.4.8
formatter-coffeescript, v0.1.1
git-log, v0.4.1
git-tab-status, v1.7.0
javascript-snippets, v1.0.0
jsformat, v0.9.0
language-groovy-cloned-from-java, v0.3.0
language-javascript-better, v1.7.1
language-javascript-jsx, v0.3.7
language-scala, v1.1.3
language-swift, v0.4.0
linter, v1.8.0
linter-javac, v1.2.0
linter-swiftc, v2.0.0
node-debugger, v1.1.8
sass-compiler, v0.4.0
scala-format, v0.1.8

# Dev
No dev packages