I have the following code:

function foo(count: number) {}

// …

foo(count: lookup);

Where lookup is number | undefined.

In this code path, I know for sure that lookup will be a number, so I have done the following:

foo(count: lookup as number);

But a better solution would have been to use the non-null assertion operator:

foo(count: lookup!);

I would like a rule that enforces this.

It should be noted in the rule docs that this conflicts with the no-non-null-assertion rule.

Alternatively, the no-non-null-assertion could be renamed to non-null-assertion and handle both ways. That might be even better.