Rethrow expression evaluation errors to cause workflow to fault

src/core/Elsa.Core/Expressions/ExpressionEvaluator.cs

@@ -45,9 +45,8 @@ namespace Elsa.Expressions
             catch (Exception e)
             {
                 _logger.LogWarning(e, "Failed to evaluate expression {Expression} using syntax {Syntax}", expression, syntax);
+                throw;
             }
-
-            return default;
         }
     }
 }