TypeScript - Unable to access FormidableError on formidable.errors

[Frederik Ødgaard Hammer]

Support plan

• Which support plan is this issue covered by? (Community, Sponsor, Enterprise): Community
• Currently blocking your project/work? (yes/no): no
• Affecting a production system? (yes/no): no

Context

• Node.js version: 18.18.2
• Release Line of Formidable (Legacy, Current, Next): Current
• Formidable exact version: ^3.4.5
• Environment (node, browser, native, OS): node
• Used with (popular names of modules): express, typescript, es6 imports

What are you trying to achieve or the steps to reproduce?

I'd like to access the FormidableError object when I'm throwing an error, this is my use case:

router.post("/user/upload", validateAuthToken, async (req, res, next) => {
    const form = formidable({
        maxFiles: 1, 
        keepExtensions: true, 
        maxFileSize: MAX_FILE_SIZE, 
        allowEmptyFiles: false,
    });

    form.parse(req, async (err, fields, files) => {
        if (err) {
            if (err instanceof formidable.errors.FormidableError) {
                return res.status(err.httpCode ? err.httpCode : 400).send(err.message);
            }
        }
    })
});

In postman I'm passing multipart formdata, where I purposely input a file above the MAX_FILE_SIZE, the error is thrown properly, but I just seem unable to get the FormidableError object.

What was the result you got?

TypeError: Cannot read properties of undefined (reading 'FormidableError')

What result did you expect?

That the above use case works

[Charlike Mike Reagent]

That's because errors export named variables with "error codes", not directly the error class.

That's a good point, we'll fix it. I think you can access the class on errors.default.

[GrosSacASacs]

Where did you see that way of using this variable ?