Postinstall hook fails with custom location for schema.prisma

Bug description

When you have schema.prisma at a non-default location, like db/schema.prisma, then running npm install results in a scary error message that confuses users.

> @prisma/client@2.1.3 postinstall /private/tmp/a1/node_modules/@prisma/client
> node scripts/postinstall.js

Error: Either provide --schema or make sure that you are in a folder with a schema.prisma file.

How to reproduce

1. Move schema.prisma to non-default location
2. Delete node_modules
3. Run npm i
4. See error

Expected behavior

I’m not sure the best solution here, but at the very least this error message should be downgraded to info or warning and remove the terminal colors (currently bright red).

In Blitz we automatically generate prisma client as part of blitz build or blitz start, so usually Blitz users never have to think about this.

Environment & setup

@prisma/cli          : 2.1.3
Current platform     : darwin
Node: 12.6.3

[pantharshit00]

I am marking this as an improvement for now as behavior is confirmed but it is not breaking.

[timsuchanek]

Thanks for reporting @flybayer! It for sure makes sense to not error in the postinstall script, but only when executing prisma generate directly.

For all the cases that a schema could not be found, we now have this warning:

If the schema was invalid or any other error caused the generation to fail, we have this info: