Function skipPropertyNull

skipPropertyNull<T, P>(prop): ((source) => Observable<{
    [X in string | number | symbol]: X extends P
        ? NonNull<T[X]>
        : T[X]
}>)
Skips / filters values which contains null for the given property. Narrows the type of the given property within the object type from T | null to just T.

Example:
```
const x: Observable<{ a: number, b: string | null }>;

const z: Observable<{ a: number, b: string }> = x.pipe(
  skipPropertyNull('b')
);
```
value { a: 1, b: 'foo' } will pass through

value { a: 1, b: null } will be skipped
Type Parameters
- T
- P extends string | number | symbol
Parameters
- prop: P
  
  name of the property to check
Returns ((source) => Observable<{
    [X in string | number | symbol]: X extends P
        ? NonNull<T[X]>
        : T[X]
}>)
- - (source): Observable<{
        [X in string | number | symbol]: X extends P
            ? NonNull<T[X]>
            : T[X]
    }>
  - Parameters
    - source: Observable<T>
    Returns Observable<{
        [X in string | number | symbol]: X extends P
            ? NonNull<T[X]>
            : T[X]
    }>
- Defined in operators/skip-property-null.ts:47