Uncaught TypeError: Cannot read property 'parentNode' of null

[kankaristo]

I just ran into this while I was messing around with another package. I was creating a view/tab and almost immediately destroying it. Probably not something that you should do, but... This doesn't seem to happen unless the tab I was destroying was the only tab.

Could some if guards be added for this?

Atom Version: 1.6.0-beta4
System: Ubuntu 15.10
Thrown From: pinned-tabs package, v0.1.12

Stack Trace

Uncaught TypeError: Cannot read property 'parentNode' of null

At /home/sami/.atom/packages/pinned-tabs/lib/pinned-tabs.coffee:186

TypeError: Cannot read property 'parentNode' of null
    at Object.module.exports.PinnedTabs.getTabInformation (/home/sami/.atom/packages/pinned-tabs/lib/pinned-tabs.coffee:186:19)
    at /home/sami/.atom/packages/pinned-tabs/lib/pinned-tabs.coffee:123:26

---

These seem to do the trick, but may not be the smartest way to solve this:

     # Get information about a tab
     getTabInformation: (e) ->
+        return unless e
         # Get related nodes
         tabbar = e.parentNode

     # Method that pins/unpins a tab given its element.
     pin: (e) ->
         # Get information about the tab
         r = @getTabInformation e
+        return unless r

         # Calculate the new index for this tab based
         # on the amount of pinned tabs within this pane.
         if r.isPinned

     # Observer panes
     observers: ->
         self = this # This object has to be stored in self because the callback function will create its own 'this'
         atom.workspace.onDidAddPaneItem (event) ->
             setTimeout (->
                 # Get information about the tab
                 r = self.getTabInformation document.querySelector('.tab-bar .tab.active')
+                return unless r

                 # Move it if necessary
                 if r.pinIndex > r.curIndex

[ericcornelissen]

Hmm, that does indeed not look like the nicest way to solve the problem... Can you explain why you also added return unless r to the pin method? Given you're description I would say it isn't necessary. And in that case, only the event(s) in observers need the check, which would make the solution less terrible. 😓

[kankaristo]

You're right, the return unless r in pin() doesn't seem to be necessary, I added it simply because getTabInformation() can now return null. I guess it would be best to do something like:

     # Observer panes
     observers: ->
         self = this # This object has to be stored in self because the callback function will create its own 'this'
         atom.workspace.onDidAddPaneItem (event) ->
             setTimeout (->
                 # Get information about the tab
-                r = self.getTabInformation document.querySelector('.tab-bar .tab.active')
+                return unless e = document.querySelector('.tab-bar .tab.active')
+                r = self.getTabInformation e

The above change alone is enough to avoid the error.

[ericcornelissen]

I changed it and ran some tests, it seems like the problem is solved (I also published it to apm)! Thanks for the help 😄