Fixes on tsdoc examples

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Found during some testing of the tsdoc @ examples present within the current codebase.

I also found one error

type B = AssertPromiseLike< { then(): void } >; 
//                                                  ^
// Type '{ then(): void; }' does not satisfy the constraint 'PromiseLike<any>'.

I don't really know how to simply fix this one by correcting the example.