There is a breaking in change in the `MatcherContext` that is passed to
matcher functions, so we now have `!!this.isNot` in a few places. The
same could happen to custom matcher in the wild.
```ts
// Old
{
isNot: boolean;
promise: string;
}
```
```ts
// New
{
isNot?: boolean;
promise?: string;
}
```
Fixes#23612.
