JS5003: Cannot assign to a function result
The code attempts to assign a value to a function result. The result of a function can be assigned to a variable, but it cannot be used as a variable. If you want to assign a new value to the function itself, omit the parentheses (the function call operator).
To correct this error
Do not use the value of a function call result as something you can assign to. You can assign the result of the function call to a variable, though.
myVar = myFunction(42);
Alternatively, you can assign the function itself (and not its return value) to a variable.
myFunction = new Function("return 42;");