Backport "Fix regression on case export" to 5.4

[mattwire]

Overview

Ref #12517 Case Export was crashing

Before

See #12517

After

See #12517

Comments

@lcdservices Don't suppose you have time to test this against 5.4rc before the release? @totten When is the release being cut?
@eileenmcnaughton This is your fix, backported to 5.4

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[lcdservices]

@mattwire I ran through tests. I didn't hit any errors. There were some enotices when exporting cases using select fields for export, but they were different from the ones previously reported, so may be unrelated.

However -- when exporting cases using primary fields, I'm seeing a lot of what appear to be duplicate rows. This may be unrelated to the intent of this PR, but is worth noting here.

[eileenmcnaughton]

@lcdservices did you hit an error WITHOUT this patch? ie. is it better WITH?

[lcdservices]

It's better with. There are the previously reported e-notices and a fatal error when exporting cases when running on 5.4 without this patch.