UnhandledPromiseRejectionWarning on Node 7.7.2

[cschroeter]

Description

Bug

Expected behavior

npm start

should not return a UnhandledPromiseRejectionWarning

Actual behavior

cschroeter@pc:~/workspace/my-first-react-app$ npm start

> test@0.1.0 start /home/cschroeter/workspace/my-first-react-app
> react-scripts start

(node:1863) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): TypeError: "listener" argument must be a function
(node:1863) DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Environment

Run these commands in the project folder and fill in their results:

1. npm ls react-scripts (if you haven’t ejected):

cschroeter@pc:~/workspace/my-first-react-app$ npm ls react-scripts
my-frist-react-app@0.1.0 /home/cschroeter/workspace/my-frist-react-app
└── react-scripts@0.9.4

2. node -v:

v7.7.2

3. npm -v:

4.3.0

Then, specify:

1. Operating system:
   Windows 10 in Linux Bash Shell Build 15048 (Creator Update)

To Reproduce

$ create-react-app my-first-react-app
$ cd my-first-react-app
$ npm start

[whelmich]

Can reproduce in Linux Mint 18.1 with the same node/npm versions.

Problem can be resolved by downgrading node to 7.7.1 or older. The problem appeared after upgrading node to 7.7.2.

[whelmich]

This problem seems to be caused by detect-port:1.0.1, used by react-scripts. It causes an error in detect-port/lib/detect-port.js on line 61 socket.connect(...).

detect-port is currently at version 1.1.0 which features a different approach of port detection. This version resolves the error for node v7.7.2, and also works with 7.6.0 and 7.7.1.

The Travis build test of version 1.1.0 of detect-port seems to fail, because the test is using node v4.8.0. On node 7.6.0, 7.7.1 and 7.7.2 the tests complete without any problems.

As the minimum node version of react-scripts is >=4 I am not sure if upgrading the version of detect-port in package.json in react-scripts is an acceptable solution as detect-ports:1.1.0 only passes its test on node version >=6.

[Timer]

We do not support Node 7, so the official recommendation would be to downgrade to the latest LTS.
Currently, that is Node v6.10.0.

However, we understand this might be desirable. Would one of you like to send a PR adding Node 7 to the CI (only one of the test cases) and resolving this issue?
Thanks!

/cc @whelmich

[gaearon]

(We definitely should support Node 7 tho)

[taivu]

I get the same error in MacOS El Capitan and Ubuntu (both node 7). Weird thing is that in Ubuntu it still runs and starts the server, but doesnt detect any changes to files. In MacOS, it just quits.

[Timer]

(We definitely should support Node 7 tho)

We should probably run all test cases on Node 7 then. 🤷‍♀️

Node 8 comes out in a month though, which I assume means we would drop Node 7 support. Worth waiting?

[gaearon]

I don't think we should skip supported versions, it would be confusing.

[vhain]

It can be bug of Node 7.7.2 and if it is, it should be fixed by nodejs/node#11762

+i think that promise should be catch somewhere

[Timer]

Ah, brilliant @vhain! This definitely looks like a regression then. 😄