Unexpected Token Error

[ckauth97]

Found in: yaml/dist/compose/composer.js

if (prelude[i + 1]?.[0] !== '#')

Not expecting the period in between the ? and [0].

Threw errors when trying to run in some cases (failed on cron job execution).

Rolled back to v2.0.1 and that seemed to stop the issue from occurring.

Full Stack Trace

yaml/dist/compose/composer.js:33
                if (prelude[i + 1]?.[0] !== '#')
                                   ^

SyntaxError: Unexpected token .
    at Module._compile (internal/modules/cjs/loader.js:723:23)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at Object.<anonymous> (node_modules/yaml/dist/index.js:3:16)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)

[eemeli]

Is this perhaps in a Node.js v12 or earlier environment? yaml@2 requires Node.js v14 or later.

[slntopp]

Node v16, same issue.
And 2.0.1 works perfectly fine.

[eemeli]

Are you able to provide a reproducible case for this? The test suite is run on Node.js v14 and v16, so this is a bit surprising.

[eemeli]

Also, are you really sure that you're seeing this with Node.js 16? In my testing, this works:

$ docker run -it --rm node:14.0.0 bash

root@2017ef9af875:/# npm i yaml
+ yaml@2.1.0
root@2017ef9af875:/# node

> let YAML=require('yaml')
> YAML.parse('%YAML 1.2\n---\n42')
42

But this fails:

$ docker run -it --rm node:12.0.0 bash

root@0a4386ec4111:/# npm i yaml
+ yaml@2.1.0
root@0a4386ec4111:/# node

> let YAML=require('yaml')
Thrown:
/node_modules/yaml/dist/compose/composer.js:33
                if (prelude[i + 1]?.[0] !== '#')
                                   ^

SyntaxError: Unexpected token .

[slntopp]

Can't tell for OP, but yes, I have a Vue app using this library, and it is most certainly running Node v16 :)

To be precise, Dockerfile building it uses 16.13, and on my computer it is 16.15

[eemeli]

@Sintopp That's really curious. Perhaps there's some JS transpiler that's failing to parse the optional chaining? In any case, a reproducible case does seem needed here to diagnose the issue further.

[ckauth97]

Also running Node v16.

Will post a reproducible scenario if I can find one.

[FelicitusNeko]

Same error, different location:

./node_modules/yaml/browser/dist/nodes/Scalar.js 13:15
Module parse failed: Unexpected token (13:15)

|   toJSON(arg, ctx) {
>     return ctx?.keep ? this.value : toJS(this.value, arg, ctx);
|   }

It looks like this library recently switched to TypeScript. Perhaps that's related?

Running Node 16.14.2, with a create-react-app on react-scripts version 4.0.3.

[eemeli]

Thank you @FelicitusNeko, that gave me enough hints to investigate. This looks like it's caused by webpack/webpack#11186, and that the kind of solutions suggested by nuxt/nuxt#7722 (comment) do help resolve this.

In other words, please try one of the following:

1. Upgrade your react-scripts or webpack dependency to their v5 releases.
2. Add something like "node 12" to your Browserslist config.

In my own testing, either of those was able to resolve this issue. If you're experiencing this and you're not using either react-scripts or webpack, please share what tools (and their versions) you are using to build your app.

[FelicitusNeko]

Unfortunately, I am unable to upgrade react-scripts to v5, and especially not webpack, as that causes major breaking changes in my project. Until that gets resolved, I'm stuck on v4.

[eemeli]

@FelicitusNeko Have you tried adding "node 12" to your Browserslist config?