Initialize list correctly! Add additional validation to prevent panic…

…s due to bugs

Signed-off-by: Rohit Nayak <rohit@planetscale.com>

go/vt/vttablet/tabletmanager/vreplication/replicator_plan.go

@@ -724,6 +724,10 @@ func (tp *TablePlan) appendFromRow(buf *bytes2.Buffer, row *querypb.Row) error {
 		return vterrors.Errorf(vtrpcpb.Code_INTERNAL, "wrong number of fields: got %d fields for %d bind locations",
 			len(tp.Fields), len(bindLocations))
 	}
+	if len(row.Lengths) < len(tp.Fields) {
+		return vterrors.Errorf(vtrpcpb.Code_INTERNAL, "wrong number of lengths: got %d lengths for %d fields",
+			len(row.Lengths), len(tp.Fields))
+	}
 
 	// Bind field values to locations.
 	var (

go/vt/vttablet/tabletmanager/vreplication/vcopier_atomic.go

@@ -155,8 +155,8 @@ func (vc *vcopier) copyAll(ctx context.Context, settings binlogplayer.VRSettings
 			lastpk = nil
 			// pkfields are only used for logging, so that we can monitor progress.
 			pkfields = make([]*querypb.Field, len(resp.Pkfields))
-			for _, f := range resp.Pkfields {
-				pkfields = append(pkfields, f.CloneVT())
+			for i, f := range resp.Pkfields {
+				pkfields[i] = f.CloneVT()
 			}
 
 			fieldEvent := &binlogdatapb.FieldEvent{