get_columns_description wrapped DBAPI connection/operational/database
errors into a generic SupersetGenericDBErrorException before they ever
reached CreateDatasetCommand's dedicated re-raise clause, making that
clause unreachable for virtual datasets. Preserve SupersetDBAPIError
subclasses the same way OAuth2RedirectError is already preserved.
DatasetRestApi.post also flattened these deliberately-unchanged
infra failures (including SupersetTimeoutException) into the generic
except Exception -> 500 "Fatal error" branch, discarding their real
status. Handle them explicitly before that branch.
Addresses PR review comments from msyavuz on apache/superset#43334.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
