in backends/sentry.js [107:118]
function computeErrLoc(msg) {
// This is the number of stack frames that exist between us and
// where the logging program called into logtron.
var error = new Error(msg);
var lines = error.stack.split('\n');
var line = lines[MAGIC_LINE_NUMBER_OFFSET];
var errLoc = line ?
line.replace(/^\s*at .*\/([^\:\/]*).*$/, "$1") : '';
return errLoc;
}