GetOrCreateStaticConstructor() fails if no global module type is present

[766F6964]

System:
System: Tested on Arch Linux x64
Kernel: 5.5.11-arch1-1
DotNet Version: 3.1.103
AsmResolver Branch: v4

Summary
The ModuleDefinition class already provides functionality to automatically create a global static constructor with the method GetOrCreateStaticConstructor() .
However, this only works, if the type is already present, otherwise GetModuleType() returns null.

Steps to reproduce:

1. Create a project with the following code

static void Main(string[] args)
{
    var assembly = new AssemblyDefinition("Test", new Version(1, 0, 0, 0));
    var moduleDefinition = new ModuleDefinition("TestModule", KnownCorLibs.NetStandard_v2_1_0_0);
    
    assembly.Modules.Add(moduleDefinition);
    assembly.ManifestModule.GetOrCreateModuleConstructor();

    Console.WriteLine("ok");
}

2. Run the code, and observe that AsmResolver throws a NullReferenceException exception, because GetModuleType() just returns null, if the type is not present:

public TypeDefinition GetModuleType() => TopLevelTypes.Count > 0 ? TopLevelTypes[0] : null;

See: ModuleDefinition.cs (L.596)

Suggestion:
Either modify GetModuleType() to GetOrCreateModuleType(), or add a second method with that functionality.
If there is already a shortcut to create a static module type constructor, there should also be a shortcut to create the global module type itself, if not present.