Using cockpit with strictNullCheck = true results in not assignable errors

[kingsleyzissou]

Explain what happens

I am importing the pkg/lib directory into an existing react/ts project (https://github.com/osbuild/image-builder-frontend).

We have strictNullCheck set to true in our tsconfig. This results in a number of errors in the pkg/lib/cockpit/channel.ts file, I'll just copy the first error for the sake of brevity.

pkg/lib/cockpit/channel.ts:31:3 - error TS2411: Property 'command' of type 'undefined' is not assignable to 'string' index type 'JsonValue'.

31   command?: never;
     ~~~~~~~

Found 7 errors in the same file, starting at: pkg/lib/cockpit/channel.ts:31

When I check the type for JSONValue I see:

export type JsonValue = | null | boolean | number | string | JsonValue[] | { [key: string]: JsonValue };

Which is an issue when strictNullCheckis set to true since undefined !== null.

Version of Cockpit

main

Where is the problem in Cockpit?

None

Server operating system

Red Hat Enterprise Linux

Server operating system version

No response

What browsers are you using?

Chrome

System log

No response

[kingsleyzissou]

Build errors:
https://github.com/osbuild/image-builder-frontend/actions/runs/12069594511/job/33657192559?pr=2603

[allisonkarlitskaya]

Please try also enabling

"exactOptionalPropertyTypes": true

in your tsconfig.json and let me know if it helps.

The issue here is that semantically command? should mean "command may or may not exist" but without exactOptionalPropertyTypes that's treated as equivalent to "the value of command may be undefined", which clearly runs headlong into our JSON type not permitting undefined.

See https://www.typescriptlang.org/tsconfig/#exactOptionalPropertyTypes

Note also that this flag is marked as "Recommended". It's frustrating that it's not enabled by default. :(

[kingsleyzissou]

Thanks yeah it does indeed get rid of those errors. Unfortunately OpenAPI codegen doesn't seem to support the flag yet (OpenAPITools/openapi-generator#14793).

I might be able to workaround it, will have to look.

[allisonkarlitskaya]

One thing we could address with this issue: documenting what tsconfig options we expect our consumers to use. It might also be worth asking the tsc folks why this option isn't the default by now...

[kingsleyzissou]

One thing we could address with this issue: documenting what tsconfig options we expect our consumers to use. It might also be worth asking the tsc folks why this option isn't the default by now...

Thanks, in the end it was okay. I just had a lot of errors to work through but I was able to configure our generated code to generate union undefined types