fix: Avoid looking up remote jquery instance if subject is not an element

[chrisbreiding]

TR-244

Should fix this flaky failure.

The error originates from this cy.readFile().then call. We try to look up the remote jQuery instance from even though the subject is not a dom element. This causes it to sometimes fail with a cross-origin error in Firefox.

This prevents attempting to look up the remote jQuery instance in cases where the subject is not a dom element.

PR Tasks

• Have tests been added/updated?

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[cypress]

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Test summary

8120 • 0 • 108 • 3

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Run details

Project	cypress
Status	Passed
Commit	ca48410
Started	Aug 17, 2020 1:51 PM
Ended	Aug 17, 2020 1:57 PM
Duration	05:59 💡
OS	Linux Debian - 10.2
Browser	Multiple

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[jennifer-shehane]

It's weird this has never failed before since this file hasn't been touched in over a year. But I guess we don't normally run docs in Firefox either.

[chrisbreiding]

It's weird this has never failed before since this file hasn't been touched in over a year. But I guess we don't normally run docs in Firefox either.

Is it new that we run the docs against Firefox? I am wondering what changed that caused this to start failing.

[chrisbreiding]

I've tried adding a test for this, but it seems impossible to reproduce reliably. At the very least, this won't create any new issues since the logic hasn't changed. It just ensures we don't try to access state('window').$ when we don't need to by moving it after the isElement() check.

[jennifer-shehane]

Yah, maybe it is new that we run docs in Firefox in develop.