## Summary
Fixing `Internal Server Error: Unexpected invalid view filter value for
filter`
Updating a select field’s options failed with an INTERNAL_SERVER_ERROR
when the field had an associated IS_NOT_EMPTY view filter.
The affected filter stored an empty string as its value:
```
operand: IS_NOT_EMPTY
value: ""
```
### Root cause
The option-update side effect treated every associated select filter
value as an option array. It attempted to parse the empty string and
then rejected the result because it was not an array.
However, IS_NOT_EMPTY is a value-less operand, so its empty value is
valid and should not participate in option recomputation.
### Fix
Skip option-value recomputation for operands that do not expect a value,
including IS_NOT_EMPTY.
Normalize legacy scalar select-filter values using the same logic as
filter validation.
Leave subfield filters unchanged.
Preserve compatibility with legacy filter-value representations until
they are migrated to the canonical JSON format.
Weiko
fdb78b35d0