From 59798ad0bde5566c8fa5d76b803fa1f733355c44 Mon Sep 17 00:00:00 2001
From: Jan Oberhauser <jan.oberhauser@gmail.com>
Date: Sun, 12 Apr 2020 18:48:41 +0200
Subject: [PATCH] :zap: Do not allow that expressions return functions

---
 packages/workflow/src/Workflow.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/workflow/src/Workflow.ts b/packages/workflow/src/Workflow.ts
index 816c009a1f..a3d069058d 100644
--- a/packages/workflow/src/Workflow.ts
+++ b/packages/workflow/src/Workflow.ts
@@ -906,7 +906,9 @@ export class Workflow {
 		// Execute the expression
 		try {
 			const returnValue = tmpl.tmpl(parameterValue, data);
-			if (returnValue !== null && typeof returnValue === 'object') {
+			if (typeof returnValue === 'function') {
+				throw new Error('Expression resolved to a function. Please add "()"');
+			} else if (returnValue !== null && typeof returnValue === 'object') {
 				if (returnObjectAsString === true)  {
 					return this.convertObjectValueToString(returnValue);
 				}