Parse the port to a number if needed, further fixing #524 (#526)

* Parse the port to a number if needed, further fixing #524

* Fix the reassignment of program.port

lib/utils/develop.js

@@ -192,15 +192,19 @@ function startServer (program) {
 }
 
 module.exports = (program) => {
- detect(program.port, (err, _port) => {
+ const port = typeof program.port === 'string'
+ ? parseInt(program.port, 10)
+ : program.port
+
+ detect(port, (err, _port) => {
  if (err) {
  console.error(err)
  process.exit()
  }
 
- if (program.port !== _port) {
+ if (port !== _port) {
  // eslint-disable-next-line max-len
- const question = `Something is already running at port ${program.port} \nWould you like to run the app at another port instead? [Y/n] `
+ const question = `Something is already running at port ${port} \nWould you like to run the app at another port instead? [Y/n] `
 
  return rlInterface.question(question, (answer) => {
  if (answer.length === 0 || answer.match(/^yes|y$/i)) {