Crash when removing <main> nodes

[MarkNijhof]

I have 2 views that are being switched out based on a route. When one view has a main [] [] node in the root and the other has not then the routing stops working when navigating away from the view with the main [] [] node in it.

https://runelm.io/c/bb4

Everything is happy when either both views have the main [] [] node or neither has it.

I also can trigger an exception:

Uncaught TypeError: Cannot read property 'parentNode' of undefined
    at applyPatchRedraw (app.js:15858)
    at applyPatch (app.js:15788)
    at applyPatchesHelp (app.js:15774)
    at applyPatch (app.js:15799)
    at applyPatchesHelp (app.js:15774)
    at applyPatches (app.js:15765)
    at updateIfNeeded (app.js:16104)

If you start with the view that has the main [] [] node in it and navigate away from it then the next navigation will trigger this error.

I can reproduce this in Chrome, Firefox and Safari the link above has a reproducable example and runs on Elm 0.18

[process-bot]

Thanks for the issue! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.