feat: Handles task failures by returning a value

[isaacsanders]

Right now, a value is not always returned, as exits, exceptions, and thrown values are not handled inside the task.

This ensures a value is always returned.

[coveralls]

Pull Request Test Coverage Report for Build 92f26a3ce27245299d6eb569fa5f8a29ce9c32dc-PR-445

• 9 of 9 (100.0%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 87.574%

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Files with Coverage Reduction	New Missed Lines	%
lib/quantum/executor.ex	1	96.55%
<!--	Total:	1		-->

Totals
Change from base Build 7d97024030b1b0b6872e54707932df5691fc9a45:	-0.1%
Covered Lines:	296
Relevant Lines:	338

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💛 - Coveralls

[maennchen]

Thanks @isaacsanders ❤️

I think it would be better to log that an exception was thrown instead of the yielded result.