Function expectToBeNull

expectToBeNull(arg: unknown): asserts arg is null
Equivalent to calling vitest.expect(arg).toBeNull() while also asserting arg to be null.
Parameters
- arg: unknown
  The variable to be asserted.
Returns asserts arg is null
undefined.
Assert
arg is null.
Example
```
const iAmNull: number | null = Math.random() >= 0 ? 10 : null;
expectToBeUndefined(iAmNull);
expect(iAmNull + 1).toBe(11);
    // ^ 'iAmNull' is possibly 'null'.
```
- Defined in src/expect.ts:118