How to replicate typescript build error in local env?

Support
,
1

I’m blocked from building my app due to a typescript error that only occurs in my netlify production build.

11:39:14 AM:         Type "boolean | undefined" is not assignable to type "boolean".
11:39:14 AM:           Type "undefined" is not assignable to type "boolean".

Having spent days on this already I’ve read other Netlify Support posts, solutions, etc. but the issue seems intractable. I accept that this is a legit warning generated by my code I simply can’t get the error to occur locally and therefore can’t validate potential fixes.

Not looking for answers about how to address the warning, my question is: what does the Netlify prod build do differently from a local ‘npm run build’ ?

2

It’s unlikely this would happen only on Netlify. We don’t run our own TypeScript or change any of your configurations. If TypeScript is reporting this, it would very likely be a problem in your codebase and if not, feel free to share a minimal reproduction.

3

Thanks for the reply. I agree it’s a problem in my codebase. Where I’m struggling is that I don’t see any warnings locally and it builds fine, it also builds fine on my Netlify dev environment, but production hits this error.

I don’t know a way to minimally reproduce the issue and am not comfortable publicly sharing details. If there’s a better way to engage support then I’ll try there.

4

As a Pro user you can also write in to the helpdesk: Support (netlify.com).

However, we’d still need the same details that we asked for here. As for how to get this error locally, can you confirm you’ve run tsc (or npx tsc) locally?