Avoid error spam when shaders fail to compile by freeing shader_data version when compilation fails

[clayjohn]

Fixes: #99263

#99263 is a regression from #90400

Previously the ShaderData class would set its member valid to false when about to compile and then set it to true if compilation was successful (both shader compilation and setting up pipelines). IIRC we removed that since we needed to shift around how the shader was compiled run asynchronously.

Then, when setting up geometry for drawing we checked if the shader_data of a material was valid, if not, we could fall back to the default material.

Now instead of checking if !shader_data->valid, we check if the shader_data->version.is_valid(). The version is allocated the first time the shader succeeds at compiling. After that, shader_data.is_valid() will always return true. Accordingly, a way to fix this is to free the version if it exists already and the compilation fails.

[Bonkahe]

Tested Mono build on windows, does what it says on the tin, I was unable to reproduce the errors when editing shaders that I saw in the latest dev build available on the website.
All the code changes look good, not sure why the checks are failing though, of course that will need sorting out.

[DarioSamo]

Makes sense to me. Just needs small changes to pass CI.

[Repiteo]

Thanks!