Button missing after opening in new tab

Bug description:
I'm running Firefox 61.0.1 (64 bit) on Linux Mint 18.3 (64 bit).
Your add-on works perfectly as long as I left-click on an image in the Google Image search results:
https://www.google.com/search?q=kittens&source=lnms&tbm=isch&sa=X
But when I do one of the following:
a) right-click + select "open in new tab"
b) shift + left-click
c) ctrl-shift + left-click
then the "view image" button is missing.
It's no big deal if you know about it, but if you don't, it can make you think that the add-on doesn't work at all.

- Are you using browser extension or userscript?
browser extension

- Is "Make GIS great again" working on other pages?
sorry, i don't understand the question :-)
the add-on is for google image search only, so what "other pages"?

- Is error disappeared when you changed extension/userscript to userscript/extension?
no, the error is the same with the userscript version

- Link to page where error occurs
https://www.google.com/search?q=kittens&source=lnms&tbm=isch&sa=X

- Screenshot of page where error occurs
left-click (works) = https://imgur.com/tNFiG75
right-click (doesn't work) = https://imgur.com/V4bJ7Xq

- Screenshot of Developer tools' "Console" (Firefox — `Control+Shift+K`, Chrome — `Ctrl+Shift+J`)
are you kidding me?
how many more hoops do i have to jump through before i can finally submit this bug report?