Catch2 Error: A type specifier is required for all declarations

I tried to build `magic_enum` in WebAssembly using Emscripten. However, it raised an error related to Catch2. I'm not sure what the problem is. `magic_enum` can be compiled to x86-64 using the same version of Clang that Emscripten 3.1.54 uses.

Emscripten version 3.1.54

This is the error message I received when compiling `magic_enum`:

```
/home/magic_enum/test/3rdparty/Catch2/include/catch2/catch.hpp:10754:28: error: a type specifier is required for all declarations
10754 | FatalConditionHandler::engage_platform() {}
```

You can reproduce the error using the commands below:

```
git clone https://github.com/Neargye/magic_enum --recursive
cd magic_enum
mkdir build
cd build
emcmake cmake -DMAGIC_ENUM_OPT_BUILD_TESTS=ON ..
emmake make
```