this version will run with npm start, but when attempting to run the built version behind nginx, it appears to have issues
callsites 
Get callsites from the V8 stack trace API
Install
$ npm install --save callsites
Usage
const callsites = require('callsites');
function unicorn() {
console.log(callsites()[0].getFileName());
//=> '/Users/sindresorhus/dev/callsites/test.js'
}
unicorn();
API
Returns an array of callsite objects with the following methods:
getTypeName: returns the type of this as a string. This is the name of the function stored in the constructor field of this, if available, otherwise the object's Class internal property.getFunctionName: returns the name of the current function, typically its name property. If a name property is not available an attempt will be made to try to infer a name from the function's context.getMethodName: returns the name of the property of this or one of its prototypes that holds the current functiongetFileName: if this function was defined in a script returns the name of the scriptgetLineNumber: if this function was defined in a script returns the current line numbergetColumnNumber: if this function was defined in a script returns the current column numbergetEvalOrigin: if this function was created using a call to eval returns a CallSite object representing the location where eval was calledisToplevel: is this a top-level invocation, that is, is this the global object?isEval: does this call take place in code defined by a call to eval?isNative: is this call in native V8 code?isConstructor: is this a constructor call?
License
MIT © Sindre Sorhus