Uncaught TypeError: editor.getRootScopeDescriptor is not a function

[keeyim]

[Enter steps to reproduce:]

1. Edit a markdown document
2. Click on the markdown preview pane
3. Error is thrown from atom-rtags-plus package

Atom: 1.21.0 x64
Electron: 1.6.9
OS: Mac OS X 10.12.6
Thrown From: atom-rtags-plus package 1.4.2

Stack Trace

Uncaught TypeError: editor.getRootScopeDescriptor is not a function

At /Users/kimmalon/.atom/packages/atom-rtags-plus/lib/util.js:41

TypeError: editor.getRootScopeDescriptor is not a function
    at Proxy.module.exports.matched_scope (/packages/atom-rtags-plus/lib/util.js:41:38)
    at OpenFileTracker.updateRecentlyViewedItems (/packages/atom-rtags-plus/lib/open-file-tracker.js:16:47)
    at Function.module.exports.Emitter.simpleDispatch (/Applications/Atom.app/Contents/Resources/app/node_modules/event-kit/lib/emitter.js:25:20)
    at Emitter.module.exports.Emitter.emit (/Applications/Atom.app/Contents/Resources/app/node_modules/event-kit/lib/emitter.js:141:34)
    at Workspace.didChangeActivePaneItemOnPaneContainer (/Applications/Atom.app/Contents/Resources/app/src/workspace.js:492:28)
    at WorkspaceCenter.paneContainer.onDidChangeActivePaneItem (/Applications/Atom.app/Contents/Resources/app/src/workspace-center.js:17:20)
    at Function.module.exports.Emitter.simpleDispatch (/Applications/Atom.app/Contents/Resources/app/node_modules/event-kit/lib/emitter.js:25:20)
    at Emitter.module.exports.Emitter.emit (/Applications/Atom.app/Contents/Resources/app/node_modules/event-kit/lib/emitter.js:141:34)
    at PaneContainer.didChangeActiveItemOnPane (/Applications/Atom.app/Contents/Resources/app/src/pane-container.js:284:26)
    at Pane.module.exports.Pane.setActiveItem (/Applications/Atom.app/Contents/Resources/app/src/pane.js:339:22)
    at Pane.module.exports.Pane.activateItemAtIndex (/Applications/Atom.app/Contents/Resources/app/src/pane.js:475:25)
    at Pane.module.exports.Pane.activatePreviousItem (/Applications/Atom.app/Contents/Resources/app/src/pane.js:440:27)
    at Pane.module.exports.Pane.removeItem (/Applications/Atom.app/Contents/Resources/app/src/pane.js:630:22)
    at Pane.module.exports.Pane.destroyItem (/Applications/Atom.app/Contents/Resources/app/src/pane.js:706:22)
    at TabBarView.module.exports.TabBarView.closeTab (/Applications/Atom.app/Contents/Resources/app/node_modules/tabs/lib/tab-bar-view.js:341:32)
    at HTMLDivElement.TabView.didClickCloseIcon (/Applications/Atom.app/Contents/Resources/app/node_modules/tabs/lib/tab-bar-view.js:229:25)

Commands

     -5:49.2.0 deprecation-cop:view (atom-workspace.workspace.scrollbars-visible-when-scrolling.seti-icons.seti-animate.theme-monokai-seti.theme-seti-ui)

Non-Core Packages

atom-rtags-plus 1.4.2 
atomic-rtags 1.3.0 
auto-detect-indentation 1.3.0 
busy-signal 1.4.3 
file-icons 2.1.12 
find-and-replace-with-prev 0.210.0 
fonts 3.0.3 
go-debug 1.5.2 
go-plus 5.5.5 
go-signature-statusbar 1.2.3 
highlight-selected 0.13.1 
hyperclick 0.1.5 
intentions 1.1.5 
json-level-color 0.1.4 
kims-markdown-package 0.0.0 
language-markdown 0.25.1 
language-plantuml 0.2.0 
last-cursor-position 0.9.2 
linter 2.2.0 
linter-ui-default 1.6.10 
markdown-preview-opener 0.1.1 
markdown-scroll-sync 2.1.2 
markdown-toc 0.4.2 
markdown-writer 2.7.2 
minimap 4.29.7 
minimap-highlight-selected 4.6.1 
monokai-seti 0.9.0 
organized 0.7.2 
pdf-view 0.59.0 
pen-paper-coffee-syntax 0.14.9 
pigments 0.40.2 
plain-simple 1.1.0 
plantuml-viewer 0.7.2 
project-manager 3.3.5 
seti-ui 1.9.0 
Sublime-Style-Column-Selection 1.7.4 
tool-bar 1.1.0 
tool-bar-markdown-writer 0.3.0 
touch-bar-utility 2.4.0