Raise in Stream.cycle when enumerable reduce call yields no elements

[lukaszsamson]

This PR reuses already existing check_cycle_first_element. I'm opening this as a draft. It fixes the infinite loop but I'm not convinced the approach is correct.

Alternatives:

• raise RuntimeError instead of ArgumentError - argument was correct, halting happens later
• refactor and pattern match on :halted directly in do_cycle

Fixes #15343

[josevalim]

The fix looks correct to me!

raise RuntimeError instead of ArgumentError - argument was correct, halting happens later

Yes, let's also do this!

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Also, the test can be simpler. You can likely use the process dictionary and no need to use tasks. If it takes too long (because of the loop), the test will timeout anyway, so you can just call Stream.cycle |> Enum.take directly and assert it raises!

[josevalim]

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