Custom tokens returning function string

So, as the title kind of suggests, using custom tokens causes the string representation of the function to be logged, not the result of the function.

Minimal Example: server.js


const path = require('path')
const app = require('express')()
const http = require('http').Server(app)
const rfs = require('rotating-file-stream')
const morgan = require('morgan')
morgan.token("local-addr",function getLocalAddrToken(req,res) {
    return req.connection.localAddress
})
//morgan.format("sal",`:local-addr HTTP :http-version :method :url ttr :response-time ms tts :total-time ms`)
morgan.format("sal",function sal(tokens,req,res) {
    return `
    ${tokens['local-addr']} HTTP${tokens['http-version'](req,res)} ${tokens.method(req,res)} ${tokens.url(req,res)} ttr ${tokens['response-time'](req,res)}ms tts ${tokens['total-time'](req,res)}ms
    ${tokens.date(req,res,"iso")}
    `
})
const logFileStream = rfs.createStream(path.resolve(__dirname,"log/access.log"),{
    interval: '1d,',
    compress: 'gzip'
})
app.use(morgan('sal',{stream: logFileStream,console: true}))
app.get('/',(req,res) => {
    res.send("<html><body></body></html>")
});
http.listen(6969,() => {
    console.log(`server listening on port: 6969`)
})

access.log output:

    function getLocalAddrToken(req,res) {
    return req.connection.localAddress
} HTTP1.1 GET / ttr 12.511ms tts 25.574ms
    2021-03-20T02:22:16.254Z

expressjs / morgan

Custom tokens returning function string #253