I am still not sure what is the full set of scenarios that the problem
might occur, but for me it occurred for an "old" cloud shell account,
and didn't reproduce since I have reconfigured it. These behavior might
be explained by the fact that "preferred shell type" did not exist in
the API originally and thus was not set. In such case, Terminal
succeeds to retrieve to the settings but then crashes when reading the
missing field. To fix it, I handle the case where the field is missing
and fallback to PowerShell.
## Validation Steps Performed
* Tested manually, only once.
Closes#7056
0c0830b2f2