[PATCH] Two small errhint cleanups in PG19 code

Hi,

While exploring new features in PG19, I came across two unrelated
small errhint issues. Sending them as separate patches in one thread since
they touch
unrelated subsystems and can be reviewed/committed independently.

Patch 0001 -- Remove stray word in pg_restore_extended_stats() errhint
The errhint in import_pg_statistic() reads:

      Value of element "%s" must be type a null or a string.

  The word "type" is a stray word that doesn't belong; the intent is
  "must be a null or a string".

Patch 0002 -- Add missing period to online data checksums errhint
  The errhint emitted when StartupXLOG() detects an interrupted
  "enabling data checksums" run is missing a trailing period:

      Data checksum processing must be manually restarted for
      checksums to be enabled

Thanks,
Baji Shaik