Errloc is an error logger that tracks every line processing an error (not just the one producing the error).

npm install errloc

Start with

var errloc = require('errloc')();

for the default format filename:line, or with

var errloc = require('errloc')('File %s, line %s.');

to provide a custom format.

errloc(callback) expects a callback(err, ...) and modifies it to log the file name and line number in case err is not null.