Fix compiler error "does not satisfy the constraint 'ObjectNested'"

[colinrotherham]

This PR fixes #5606

Affects ConfigurableComponent<CustomConfig> in v5.8.0 where CustomConfig doesn't extend ObjectNested

   * @virtual
-  * @template {ObjectNested} [ConfigurationType={}]
+  * @template {Partial<Record<keyof ConfigurationType, unknown>>} [ConfigurationType=ObjectNested]
   * @template {Element & { dataset: DOMStringMap }} [RootElementType=HTMLElement]
   * @augments GOVUKFrontendComponent<RootElementType>

I've shared the config type via Schema Schema<ConfigurationType> for use in @param and @returns too

This may not have affected JSDoc due to The Empty Object Type in TypeScript

[romaricpascal]

Looks good, thanks for the update 🙌🏻

It makes sense to describe the ConfigurationType received by the functions that receive a configuration from the markup or component constructor with Partial<Record<keyof ConfigurationType, unknown>> as it's more representative of the expected situation.

Only one little stylistic suggestion for that for loop in normaliseDataset which is a bit heavy with the casting in the middle of it, would be great to have that as a variable before the loop. I'll approve in the meantime.

[romaricpascal]

Recording what we understood during the review

• namespace is a keyof ConfigurationType which will be passed to extractConfigByNamespace which also requires a keyof ConfigurationType
• field needs to be a string so it can be used to access dataset (a DOMStringMap and fill out (an ObjectNested, whose keys are string)

[romaricpascal]

suggestion Having the casting outside of the for loop would increase readability:

Suggested change

	for (const entries of /** @type {[keyof ConfigurationType, SchemaProperty | undefined][]} */ (
	Object.entries(Component.schema.properties)
	)) {
	const [namespace, property] = entries
	const field = namespace.toString()
	const entries = /** @type {[keyof ConfigurationType, SchemaProperty | undefined][]} */ (
	Object.entries(Component.schema.properties)
	)
	for (const entry of entries) {
	const [namespace, property] = entry
	// Cast the `namespace` to string so it can be used to access the dataset
	const field = namespace.toString()

[colinrotherham]

Thanks @romaricpascal @domoscargin

Just pushed. How's this? ab3d188

[domoscargin]

LGTM - running checks now

[domoscargin]

Thanks @colinrotherham!