useEntityRecord: Fix destructure error when enabled option is false

[t-hamano]

Fixes: #51466
Related to #39288

What?

This PR fixes an error that occurs when { enabled: false } is specified in the fourth argument of useEntityRecord.

For example, when you write code like this:

const { record, isResolving } = useEntityRecord( 'postType', 'page', 1, {
	enabled: false,
} );

The following error is logged in the browser console:

use-entity-record.ts:182 Uncaught TypeError: Cannot destructure property 'data' of '(0 , _use_query_select__WEBPACK_IMPORTED_MODULE_4__.default)(...)' as it is null.

Why?

This is because if enabed is false, the internal useQuerySelect returns null and the data property cannot be destructured.

How?

I referred to getEntityRecords implementation, but I think it should be the value of the data property that is null, not the entire object.

Testing Instructions

Confirm that the following code does not cause an error.

The record variable should be the post object if the post exists, or undefined if it does not:

const { record } = useEntityRecord( 'postType', 'page', 2 );

const { record } = useEntityRecord( 'postType', 'page', 2, {
	enabled: true,
} );

The record variable should always be null:

const { record } = useEntityRecord( 'postType', 'page', 2, {
	enabled: false,
} );

[Mamaduka]

Thanks, @t-hamano!