Allow Psalm to kill mutant on uncovered line of code.

[bdsl]

Similar to #486 (and perhaps more so) this might not be feasible to fix, but it does seem desirable. For some parts of many projects it's probably reasonable to decide that high type coverage with highly specific Psalm types is sufficient and unit tests are not needed.

If it'd not feasible then take this issue as documentation issue - either the issue itself can serve as documentation or I can contribute to the readme or other docs.

[Ocramius]

high type coverage with highly specific Psalm types is sufficient and unit tests are not needed.

Code should still be run at least once, unless all it produces is a static compilation output (not applicable to PHP).

Running without phpunit (solely psalm) is feasible though.