Fix #130555: Vulkan: Crash when using legacy gpu API

Add-ons can still use the legacy API that only works on OpenGL. Vulkan
however was crashing as there is no shader create info available.

Adding a pre-check when finalizing shaders on availability of shader
create info.

Pull Request: https://projects.blender.org/blender/blender/pulls/130660

source/blender/gpu/vulkan/vk_shader.cc

@@ -583,6 +583,11 @@ bool VKShader::finalize(const shader::ShaderCreateInfo *info)
   if (compilation_failed) {
     return false;
   }
+  /* Add-ons that still use old API will crash as the shader create info isn't available.
+   * See #130555 */
+  if (info == nullptr) {
+    return false;
+  }
 
   if (do_geometry_shader_injection(info)) {
     std::string source = workaround_geometry_shader_source_create(*info);