fix(editor): Restrict [empty] in parameter input hint to zero-length string

cypress/e2e/14-mapping.cy.ts

@@ -205,7 +205,7 @@ describe('Data mapping', () => {
 				'have.text',
 				`{{ $node['${SCHEDULE_TRIGGER_NODE_NAME}'].json.input[0].count }} {{ $node['${SCHEDULE_TRIGGER_NODE_NAME}'].json.input }}`,
 			);
-		ndv.getters.parameterExpressionPreview('value').should('include.text', '[empty]');
+		ndv.getters.parameterExpressionPreview('value').should('have.text', ' ');
 
 		ndv.actions.selectInputNode('Set');
 

packages/editor-ui/src/components/ParameterInputHint.vue

@@ -1,11 +1,6 @@
 <template>
 	<n8n-text size="small" color="text-base" tag="div" v-if="hint">
-		<div
-			v-if="!renderHTML"
-			:class="{ [$style.singleline]: singleLine, [$style.highlight]: highlight }"
-		>
-			{{ hint }}
-		</div>
+		<div v-if="!renderHTML" :class="classes">{{ hint }}</div>
 		<div
 			v-else
 			ref="hint"
@@ -39,6 +34,15 @@ export default defineComponent({
 	methods: {
 		sanitizeHtml,
 	},
+	computed: {
+		classes() {
+			return {
+				[this.$style.singleline]: this.singleLine,
+				[this.$style.highlight]: this.highlight,
+				[this.$style['preserve-whitespace']]: true,
+			};
+		},
+	},
 	mounted() {
 		if (this.$refs.hint) {
 			(this.$refs.hint as Element).querySelectorAll('a').forEach((a) => (a.target = '_blank'));
@@ -56,4 +60,7 @@ export default defineComponent({
 .highlight {
 	color: var(--color-secondary);
 }
+.preserve-whitespace {
+	white-space: pre;
+}
 </style>

packages/editor-ui/src/components/ParameterInputWrapper.vue

@@ -182,8 +182,8 @@ export default mixins(showMessage, workflowHelpers).extend({
 					return null;
 				}
 
-				if (typeof computedValue === 'string' && computedValue.trim().length === 0) {
-					computedValue = this.$locale.baseText('parameterInput.emptyString');
+				if (typeof computedValue === 'string' && computedValue.length === 0) {
+					return this.$locale.baseText('parameterInput.emptyString');
 				}
 			} catch (error) {
 				computedValue = `[${this.$locale.baseText('parameterInput.error')}: ${error.message}]`;