[tbb-bugs] #29451 [Applications/Tor Browser]: document.body must not return null at document_end state

[Tor Bug Tracker & Wiki]

#29451: document.body must not return null at document_end state
-------------------------+------------------------------------------
 Reporter:  cypherpunks  |          Owner:  tbb-team
     Type:  defect       |         Status:  new
 Priority:  Medium       |      Component:  Applications/Tor Browser
  Version:               |       Severity:  Major
 Keywords:               |  Actual Points:
Parent ID:               |         Points:
 Reviewer:               |        Sponsor:
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 Manifest: "content_scripts":[{ "all_frames": true, "matches":
 ["https://*/*"], "js": ["test.js"], "run_at": "document_end" }],

 test.js: document.body.addEventListener(...)

 And try to open this page:
 https://via.hypothes.is/https://lists.torproject.org/pipermail/tor-
 onions/2019-January/thread.html


 Final Result: "TypeError: document.body is null" in Browser Console.

 Expected result: No error, because the script run at document_end

 Tested on: Tor Browser 8.0.5

 May affect on: Firefox 60.5.0esr

 The reason why I post this here is bugzilla.mozilla.org doesn't let me
 create an account. Go easy on me.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29451>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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