fix(endWith): wrap args - they are not observables - in of before concatenating

[cartant]

Description:

This PR spreads the arguments passed to endWith into a call to of which is then passed to `concat.

The current implementation spreads the args directly into concat which is incorrect. The tests pass because strings are iterable and are therefore valid observable inputs. And the strings in the tests each contain only a single character. The test added in this PR uses numbers for values, and their use effects an error from the current, incorrect endWith implementation.

Related issue (if exists): #4731

[coveralls]

Pull Request Test Coverage Report for Build 8438

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.0005%) to 96.857%

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Totals
Change from base Build 8414:	0.0005%
Covered Lines:	5793
Relevant Lines:	5981

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💛 - Coveralls

[benlesh]

Oh wow! What a cool bug that made it through all of those tests! Since 'x' is an iterable, concat(obs$, 'x') is the same thing as concat(obs$, of('x')). 🤣

[AlexAegis]

In v6.5.1 this worked:

endWith(of(undefined))

In v6.5.2 this works, just as the changelog says:

endWith(undefined)

But right now in v6.5.2 endWith(undefined) is marked as deprecaded. Am I doing something wrong or is this a bug?

[cartant]

@alex-wilmer It's matching the signature with the scheduler in it. Most likely because you do not have strictNullChecks enabled. See this comment and this comment.

As mentioned in the latter comment, IMO, the deprecation in the TSDoc should not be removed to avoid the match in situations in which strictNullChecks are disabled. Override the lint failure using the mechanism mentioned in that comment.

IMO, this is a documentation issue.