Fix handling of default onddl

Signed-off-by: Matt Lord <[email protected]>

go/vt/vtctl/workflow/materializer.go

@@ -179,7 +179,10 @@ func (mz *materializer) generateBinlogSources(ctx context.Context, targetShard *
 			ExternalCluster: mz.ms.ExternalCluster,
 			SourceTimeZone:  mz.ms.SourceTimeZone,
 			TargetTimeZone:  mz.ms.TargetTimeZone,
-			OnDdl:           binlogdatapb.OnDDLAction(binlogdatapb.OnDDLAction_value[mz.ms.OnDdl]),
+		}
+		// If no valid value is found, the default for on_ddl is implicitly "IGNORE".
+		if val, ok := binlogdatapb.OnDDLAction_value[strings.ToUpper(mz.ms.OnDdl)]; ok {
+			bls.OnDdl = binlogdatapb.OnDDLAction(val)
 		}
 
 		var tenantClause *sqlparser.Expr