COMP: Remove unused variable
ENH: Initialize all arrays in `LabelSetUtils.h` file
STYLE: Remove unnecessary/empty comment statements in tests
STYLE: Remove unreachable `break` after `return` statement
STYLE: Remove unnecessary brackets around `EXIT_FAILURE`
STYLE: Conform to ITK style guidelines in test arg check
STYLE: Make the input argument checking be the first task in tests
STYLE: Use `ITK_TRY_EXPECT_NO_EXCEPTION` macro in tests