Merge 75da839d93 into 0ce820de73

packages/@n8n/tournament/src/ExpressionSplitter.ts

@@ -25,6 +25,12 @@ const normalizeBackslashes = (text: string): string => {
 };
 
 export const splitExpression = (expression: string): ExpressionChunk[] => {
+	// Maintain the "always have an initial text chunk" invariant
+	// that ExpressionBuilder.getExpressionCode relies on.
+	if (expression === '') {
+		return [{ type: 'text', text: '' }];
+	}
+
 	const chunks: ExpressionChunk[] = [];
 	let searchingFor: 'open' | 'close' = 'open';
 	let activeRegex = OPEN_BRACKET;

packages/workflow/src/extensions/expression-parser.ts

@@ -22,6 +22,12 @@ export const escapeCode = (text: string): string => {
 };
 
 export const splitExpression = (expression: string): ExpressionChunk[] => {
+	// Mirror @n8n/tournament's splitExpression: always emit an initial text
+	// chunk so downstream consumers can rely on chunks[0] being defined.
+	if (expression === '') {
+		return [{ type: 'text', text: '' }];
+	}
+
 	const chunks: ExpressionChunk[] = [];
 	let searchingFor: 'open' | 'close' = 'open';
 	let activeRegex = OPEN_BRACKET;

packages/workflow/test/ExpressionExtensions/expression-extension.test.ts

@@ -69,6 +69,10 @@ describe('Expression Parser', () => {
 				{ type: 'code', text: ' code.test("}}") ', hasClosingBrackets: true },
 			]);
 		});
+
+		test('Empty input (CAT-3075)', () => {
+			expect(splitExpression('')).toEqual([{ type: 'text', text: '' }]);
+		});
 	});
 
 	describe('Compatible joining', () => {

packages/workflow/test/expression.test.ts

@@ -778,6 +778,14 @@ describe('Expression', () => {
 			});
 		});
 
+		// CAT-3075: feature parity between legacy and VM engines for empty expressions.
+		// The legacy engine returns "" via Tournament.execute's empty-input guard;
+		// the VM engine bypassed that guard and threw
+		// `TypeError: Cannot read properties of undefined (reading 'text')`.
+		it('should resolve "=" (empty expression marker) to "" (CAT-3075)', () => {
+			expect(evaluate('=')).toBe('');
+		});
+
 		describe('additionalKeys', () => {
 			const node = workflow.nodes.node;