The fact that I can't think of how to do this makes me think it's some sort of anti-pattern, or impossible. If anyone has any better ideas of how to handle my situation, recommendations always welcome.
I have a legacy codebase and at one point I am retrieving function references and calling the function. These function calls are expected to return a result, but sometimes they are missing their return statement. Currently I throw an error if the returned value is nullish but this only gives me a stacktrace to the engine location that is calling the function, not the function itself.
Is there any way that I can determine the file name/number of the function, or force the function to throw an error such that a stacktrace to that actual function is generated?
There is no such feature in the Javascript language. It's not anti-pattern, just not something that the language supports. There is no requirement that a function have a return statement and there is no way to force it to throw an exception if it doesn't return a value.
Without seeing any of the relevant code, I can offer some suggestions:
Set a breakpoint at the line of your code that initiates the function call. Then, trace into the function in the debugger. You can go as far into it as you need to and each time you go step into a new function call, it will show you the file and line number that you're on. I use this technique regularly when I'm confused by some behavior by some module (either built-in to nodejs or an external module I'm using) and it's not immediately clear how to find the right code on Github for it. I just step into it and can immediately see the code and watch it execute line by line as needed for whatever problem I'm investigating.
Assuming this function you're calling expects some arguments, you can give it some sort of bogus arguments that would hopefully trigger it to throw some sort of exception and you could then see the stack trace from that exception. For example, if it was expecting a non-optional object as an argument, you could pass null and see if that triggers an exception. If it was expecting a callback, you could pass a non-function and see if that triggered an exception.
As for the name of the function, if the function has an actual name (it's not anonymous) and fn is your function reference, then you can do console.log(fn.name) and see if there is a name. You could also examine fn.toString() and see if it reveals the source code of the function. Sometimes it will and if the function is a named function that may show you its name. This won't show you what file it's in, but you could perhaps then grep for something you see in the source to find it.
Here's an example from point #3:
function hello() {
return "hi";
}
// create function reference that points to my function
const fn = hello;
// log info on that function reference
console.log(fn.name);
console.log(fn.toString());