Wrong typescript definition for serializeError

[ghost]

If I am understanding the TypeScript correctly,

https://www.typescriptlang.org/docs/handbook/2/generics.html#working-with-generic-type-variables

https://github.com/sindresorhus/serialize-error/blob/main/index.js#L160

If the value input is function,

Should the type of return value must be also function as well?

If we still want to convert function value to string,

The type definition for input & return value should be any or unknown since they don't share the same type.

export function serializeError(error: any, options?: Options): any

[papb]

Should the type of return value must be also function as well?

No...

If we still want to convert function value to string,

According to this test, yes we do.

The type definition for input & return value should be any or unknown since they don't share the same type.

There's nothing wrong with input type and return type not sharing the same type.

[papb]

Also, in the future, prefer using a permalink when linking to code. So instead of

https://github.com/sindresorhus/serialize-error/blob/main/index.js#L160

You should use:

https://github.com/sindresorhus/serialize-error/blob/2a77169cae632802b75c9962b8ae9a482c978ae2/index.js#L160

To get this link:

[ghost]

There's nothing wrong with input type and return type not sharing the same type.

@papb What I wanted to say is that the current type definition is wrong

https://github.com/sindresorhus/serialize-error/blob/main/index.d.ts#L108

Type definition is enforcing that the return value should have the same type of the input, while we convert function inputs to string

[fregante]

Type definition is enforcing that the return value should have the same type of the input

That is correct. serializeError returns the same value if it's not an object and not a function

serialize-error/index.js

Lines 141 to 166 in 2a77169

	export function serializeError(value, options = {}) {
	const {
	maxDepth = Number.POSITIVE_INFINITY,
	useToJSON = true,
	} = options;
	if (typeof value === 'object' && value !== null) {
	return destroyCircular({
	from: value,
	seen: [],
	forceEnumerable: true,
	maxDepth,
	depth: 0,
	useToJSON,
	serialize: true,
	});
	}
	// People sometimes throw things besides Error objects…
	if (typeof value === 'function') {
	// `JSON.stringify()` discards functions. We do too, unless a function is thrown directly.
	return `[Function: ${value.name ?? 'anonymous'}]`;
	}
	return value;
	}

The logic is simply:

• if it's an object, return an object
• if it's a function, return a string
• if it's anything else, return it as is

The return is never unknown. Even if it is, we know it's Input, so we return it as such.