FIX: make code compile under C++20

[texel-sensei]

In the destructor of the igtlLightObject, a call to std::uncaught_exception was used. This function was deprecated in C++17 and then removed in C++20, which causes OpenIGTLink to fail compilation on Visual Studio if C++20 is enabled. Judging from the comments in the code, the call was unnecessary, so it was removed.

[leochan2009]

Hi, though the chance is low, the uncaught exception might still pose some value here. As well as for the backward compatibility concern, could we follow the link here? https://github.com/doctest/doctest/pull/340/commits/e61a0708b205459e478dfaa94dcb82f5b015334a

[texel-sensei]

The code guarded by the if does not throw an exception, as that line was commented out and replaced by a warning.

And no matter the guard, if an exception would actually be thrown at this part, the program would exit via std::terminate. Since C++11 all destructors are implicitly defined as noexcept, so throwing an exception here would be a throw from a noexcept(true) function, which results in terminating the program.

Edit: To elaborate further, I did actually have a version that used the feature test macros to conditionally switch between std::uncaught_exception and std::uncaught_exceptions in the beginning. But I decided against that solution, as it introduces a lot more code, for what is at the end the printout of a single warning. I would argue that the behaviour without the uncaught exceptions check is even better than previously. The warning is printed in a case where basically everything is lost. So it's better to always see this warning, to aid in debugging instead of surpressing it when there is currently an exception propagating.

[leochan2009]

@texel-sensei , it seems good to me. @tokjun , if there is no further concern, i will merge this pull request.

[tokjun]

@leochan2009 yes it sounds good to me. Thank you, @texel-sensei @leochan2009