OptionalerrorUnderlying error when success is false.
Which phase failed. Null when success is true. fulltext-generate
is the caller-side failure to GENERATE the full-text DDL, as distinct
from fulltext, the provider's failure to EXECUTE it.
True only when every requested phase succeeded.
Result of a phased per-entity SQL execution. Reports which phase (if any) failed so the caller can aggregate a per-entity diagnostic without bisecting.