fixed optional migration condition

note: practically even the previous version should work ok because the json field didn't have previous options anyway and if it was nil the migration will fail

migrations/1702134272_set_default_json_max_size.go

@@ -28,7 +28,7 @@ func init() {
 				}
 
 				options, _ := f.Options.(*schema.JsonOptions)
-				if options != nil {
+				if options == nil {
 					options = &schema.JsonOptions{}
 				}
 				options.MaxSize = 2000000 // 2mb