Workaround for known yaml-cpp iterator bug

[anderkve]

While working on GAMBIT-light, @idamarie1303, @ahye and I encountered a strange problem with YAML::Node loop iterators going beyond the size of given node, leading to a crash. (It's a tricky bug, because it only appears for some compiler settings / systems). It turns out this is a known bug in yaml-cpp, discussed here: jbeder/yaml-cpp#833

In GAMBIT-light we have so far opted for the workaround suggested here: jbeder/yaml-cpp#833 (comment).

Here's a part of LightBit.cpp in GAMBIT-light which demonstrates the fix: https://github.com/GambitBSM/gambit_light/blob/b6af795c22404d72ba39fbc3047358b6964b0b3b/LightBit/src/LightBit.cpp#L116-L150

Throughout GAMBIT I think we have around 10--20 iterator-based loops over YAML::Node instances, so to guard against this yaml-cpp bug we should probably implement this workaround also for all these loops.

[ChrisJChang]

I think you might already be aware of this, but this fix breaks the build on LUMI. Gambit-light will seg fault during the initialisation when it is looping over a yaml node. This does not happen if you loop over the iterator in the way we usually do in gambit yaml parsing.

[anderkve]

Yes -- it's strange, as it's been working fine on other systems. But with this small change in GAMBIT-light it seems to work well on LUMI: GambitBSM/gambit_light@7abc92f