msvc builds cause warning `c4530`

[Repiteo]

Godot version

v4.2.beta.custom_build [5ee983188]

godot-cpp version

c1196a1

System information

Windows 11

Issue description

Recently, my godot-cpp builds have had their logs absolutely FLOODED with this message en-masse:

C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.37.32822\include\vector(1612): warning C4530: C++ exception handler used, but unwind semantics are not enabled. Specify /EHsc
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.37.32822\include\vector(1601): note: while compiling class template member function 'void std::vector<GDExtensionClassMethodArgumentMetadata,std::allocator<GDExtensionClassMethodArgumentMetadata>>::_Reallocate_exactly(const unsigned __int64)'
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.37.32822\include\vector(1685): note: see the first reference to 'std::vector<GDExtensionClassMethodArgumentMetadata,std::allocator<GDExtensionClassMethodArgumentMetadata>>::_Reallocate_exactly' in 'std::vector<GDExtensionClassMethodArgumentMetadata,std::allocator<GDExtensionClassMethodArgumentMetadata>>::reserve'
D:\Godot\godot-libusb\godot-cpp\include\godot_cpp/core/method_bind.hpp(134): note: see the first reference to 'std::vector<GDExtensionClassMethodArgumentMetadata,std::allocator<GDExtensionClassMethodArgumentMetadata>>::reserve' in 'godot::MethodBind::get_arguments_metadata_list'
D:\Godot\godot-libusb\godot-cpp\include\godot_cpp/core/method_bind.hpp(131): note: see reference to class template instantiation 'std::vector<GDExtensionClassMethodArgumentMetadata,std::allocator<GDExtensionClassMethodArgumentMetadata>>' being compiled

I haven't been actively building a gdextension up until this past week or so, so I can't speak for how long this has potentially been in place. The last time I was actively building was late July, and it wasn't present at that time

Steps to reproduce

1. build with msvc
2. cry

Minimal reproduction project

N/A

[dsnopek]

Hm, this sounds like it's related to PR #1216 which disabled exceptions by default. We do use STL a bit in godot-cpp - I wonder if that means exceptions need to be enabled?

Do you still get the error when you build with scons disable_exceptions=no?

[Repiteo]

I tried building with that & the warning still appeared

[Repiteo]

Wait, I figured it out! The is_msvc define wasn't working because the order was out of wack! We never realized this because it was using the problematic env.get("is_msvc", False): syntax instead of ensuring a valid value ahead of time and then using env[is_msvc]. This is the same issue that I was already addressing in another PR, but I never expanded it to is_msvc there; I'll do that now and link it after!