Filtering or loading the elements lists sometimes results in one or more LookupError entries in the log

[LeonarddeR]

Steps to reproduce:

1. Open www.nu.nl in either Firefox 58 or Chrome
2. Open the elements list
3. Press tab, and enter a word to filter on
4. Press shift+tab

Expected behavior:

The list properly filters.

Actual behavior:

Multiple LookupErrors are raised.

System configuration:

NVDA version: Both 2017.4 and next
NVDA Installed or portable: Installed
Windows version: Windows 10 fall creators update

Other questions:

Does the issue still occur after restarting your PC?
Not yet tested, but we should catch these LookupErrors anyway

[LeonarddeR]

Regression caused by #6131. Note that the impact doesn't seem to be very heavy, as for release builds these errors are silenced anyway.

[LeonarddeR]

Hmm, turns out that the impact is that heavy that, when one of these LookupErrors occurs, all retrieval of other elements is ceased.
@michaelDCurran: Do you have any thoughts? Why should VirtualBufferTextInfo._getControlFieldAttribs even return a LookupError (i.e. do you know of situations where this would be the case)?

[LeonarddeR]

According to @fisher729, this also occurs when loading the elements list without filtering. I think this deserves a p2.

[LeonarddeR]

I've just received another report of this issue.

@michaelDCurran: Do you have any thoughts? Why should VirtualBufferTextInfo._getControlFieldAttribs even return a LookupError (i.e. do you know of situations where this would be the case)?

[Adriani90]

Still reproducible in NVDA alpha-28179,345154a6 (2023.2.0.28179) and all browsers. Element list in MS Word or Excel is not impacted.