[Editor] Avoid error when an editor is unselected during the pdf.js closing

[calixteman]

It aims to fix an error I noticed in the logs:
JavaScript error: http://127.0.0.1:65159/build/generic/build/pdf.mjs, line 15847: TypeError: can't access property "div", currentLayer is undefined

[calixteman]

/botio integrationtest

[moz-tools-bot]

From: Bot.io (Linux m4)

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Received

Command cmd_integrationtest from @calixteman received. Current queue size: 0

Live output at: http://54.241.84.105:8877/dd5d609a5cf54ed/output.txt

[moz-tools-bot]

From: Bot.io (Windows)

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Received

Command cmd_integrationtest from @calixteman received. Current queue size: 1

Live output at: http://54.193.163.58:8877/c9c8ddfbc9e6aa6/output.txt

[moz-tools-bot]

From: Bot.io (Linux m4)

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Success

Full output at http://54.241.84.105:8877/dd5d609a5cf54ed/output.txt

Total script time: 8.40 mins

• Integration Tests: Passed

[moz-tools-bot]

From: Bot.io (Windows)

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Success

Full output at http://54.193.163.58:8877/c9c8ddfbc9e6aa6/output.txt

Total script time: 18.00 mins

• Integration Tests: Passed

[timvandermeij]

The change looks good, but the error is still visible in the Windows logs above. Are there perhaps more places that need to be changed? Since it happens near a FreeText test, is

pdf.js/src/display/editor/freetext.js

Line 425 in 2d25437

currentLayer.div.append(this.div);

perhaps the culprit given a quick search for currentLayer.div usage?

I do wonder why we would even get in either place if the viewer is already closing, so to make sure we're not wallpapering over an actual issue: is that expected to happen in the first place, or is this error a symptom of another problem?

[timvandermeij]

Marking as needs-work because of the question above and I noticed I had an open review request for this.