diff --git a/packages/editor-ui/src/components/ParameterInput.vue b/packages/editor-ui/src/components/ParameterInput.vue
index 74c123b521..9f65d462e4 100644
--- a/packages/editor-ui/src/components/ParameterInput.vue
+++ b/packages/editor-ui/src/components/ParameterInput.vue
@@ -276,7 +276,7 @@ export default mixins(
 					returnValue = this.expressionValueComputed;
 				}
 
-				if (returnValue !== undefined && this.parameter.type === 'string') {
+				if (returnValue !== undefined && returnValue !== null && this.parameter.type === 'string') {
 					const rows = this.getArgument('rows');
 					if (rows === undefined || rows === 1) {
 						returnValue = returnValue.toString().replace(/\n/, '|');