ow.create does not return an Assertion Functions type / asserts annotation is missing

[sounisi5011]

Currently, ow() funciton is of type Assertion Functions.

ow/source/index.ts

Lines 31 to 46 in f26115d

	/**
	Test if the value matches the predicate. Throws an `ArgumentError` if the test fails.
	@param value - Value to test.
	@param predicate - Predicate to test against.
	*/
	<T>(value: unknown, predicate: BasePredicate<T>): asserts value is T;
	/**
	Test if `value` matches the provided `predicate`. Throws an `ArgumentError` with the specified `label` if the test fails.
	@param value - Value to test.
	@param label - Label which should be used in error messages.
	@param predicate - Predicate to test against.
	*/
	<T>(value: unknown, label: string, predicate: BasePredicate<T>): asserts value is T;

However, the ReusableValidator returned by ow.create() is not an Assertion Functions type.
ReusableValidator returns a void type!
In addition, the value argument does not seem to be of type unknown...

ow/source/index.ts

Lines 53 to 60 in f26115d

	/**
	Test if the value matches the predicate. Throws an `ArgumentError` if the test fails.
	@param value - Value to test.
	@param label - Override the label which should be used in error messages.
	*/
	// eslint-disable-next-line @typescript-eslint/prefer-function-type
	(value: T, label?: string): void;

For this reason, using ow.create() in TypeScript does not provide proper type validation.

[cpiber]

I have added something to help with this in #224. The problem why we can't simply write asserts value is T instead of void here is the same why the following exists:

ow/source/index.ts

Lines 122 to 125 in 3384c4e

	// Can't use `export default predicates(modifiers(ow)) as Ow` because the variable needs a type annotation to avoid a compiler error when used:
	// Assertions require every name in the call target to be declared with an explicit type annotation.ts(2775)
	// See https://github.com/microsoft/TypeScript/issues/36931 for more details.
	const _ow: Ow = predicates(modifiers(ow)) as Ow;