## Summary
- Fixes a bug where removing an option from a MULTI_SELECT field fails
with `invalid input value for enum` when existing records contain the
removed value alongside surviving values.
- The root cause was the `ELSE` branch in `updateArrayEnum` which tried
to cast removed enum values (e.g. `DISTRIBUTOR`) to the new enum type
that no longer includes them.
- The fix replaces the `ELSE` cast with a NULL-producing implicit CASE
default and uses `array_agg(...) FILTER (WHERE mapped_value IS NOT
NULL)` to silently strip removed values from existing arrays.
### Before (bug)
```sql
-- ELSE branch tries to cast removed value to new enum → crash
CASE unnest_value::text
WHEN 'IMPL' THEN 'IMPL'::new_enum
WHEN 'APP' THEN 'APP'::new_enum
ELSE unnest_value::text::new_enum -- 'DISTRIBUTOR' fails here
END
```
### After (fix)
```sql
-- No ELSE: removed values produce NULL, filtered out by array_agg
SELECT array_agg(mapped_value) FILTER (WHERE mapped_value IS NOT NULL)
FROM (
SELECT CASE unnest_value::text
WHEN 'IMPL' THEN 'IMPL'::new_enum
WHEN 'APP' THEN 'APP'::new_enum
END AS mapped_value
FROM unnest(old_column) AS unnest_value
) enum_mapping
```
