fix: add missing error check for WriteChangelogState in initiateApplier (#1623)

The WriteChangelogState call at line 1365 was missing error handling,
which could cause the migration to fail silently if the changelog table
was not properly created. This resulted in cryptic "Table doesn't exist"
errors later in the migration process.

All other calls to WriteChangelogState in the codebase properly check
for errors. This change makes error handling consistent and provides
clearer error messages when changelog table operations fail.

Co-authored-by: Claude Sonnet 4.5 <[email protected]>

Author: ajm188

go/logic/migrator.go

@@ -1362,7 +1362,9 @@ func (this *Migrator) initiateApplier() error {
 				return err
 			}
 		}
-		this.applier.WriteChangelogState(string(GhostTableMigrated))
+		if _, err := this.applier.WriteChangelogState(string(GhostTableMigrated)); err != nil {
+			return err
+		}
 	}
 
 	// ensure performance_schema.metadata_locks is available.