IsUserDefinedTypeWithEquals NullRefException

[jetdog8808]

Describe the bug in detail:
Trying to use .Remove on a UdonSharpBehaviour inherited class list, and get a compile error.

Provide steps/code to reproduce the bug:
Create a List of a UdonSharpBehaviour inherited class not overriding Equals method.
Then use .Remove, .Contains, or .IndexOf on that list.
Compile and error should pop up.

Expected behavior:
There should be no error.

Additional Information:

UdonSharp/Packages/com.merlin.UdonSharp/Editor/Compiler/Binder/BoundNodes/BoundInvocationExpression.cs

Lines 117 to 153 in f5ecf68

	else if (symbol.Name == nameof(UdonSharpInternalUtility.IsUserDefinedTypeWithEquals))
	{
	// Return constant value based on if generic type is a user defined type with Equals
	TypeSymbol typeArg = symbol.TypeArguments[0];
	bool isUserDefinedTypeWithEquals = typeArg.IsUdonSharpBehaviour || typeArg is ImportedUdonSharpTypeSymbol;
	if (isUserDefinedTypeWithEquals)
	{
	// Check if the type has an Equals method
	IEnumerable<MethodSymbol> equalsMethods = typeArg.GetMembers<MethodSymbol>("Equals", context);
	isUserDefinedTypeWithEquals = equalsMethods.Any(e => e.Parameters.Length == 1 &&
	e.ReturnType == context.GetTypeSymbol(SpecialType.System_Boolean) &&
	e.Parameters[0].Type == context.GetTypeSymbol(SpecialType.System_Object));
	TypeSymbol objectType = context.GetTypeSymbol(SpecialType.System_Object);
	if (typeArg.IsUdonSharpBehaviour)
	{
	while (!isUserDefinedTypeWithEquals && typeArg != null && typeArg.IsUdonSharpBehaviour)
	{
	if (typeArg.BaseType == objectType)
	break;
	equalsMethods = typeArg.BaseType.GetMembers<MethodSymbol>("Equals", context);
	isUserDefinedTypeWithEquals = equalsMethods.Any(e => e.Parameters.Length == 1 &&
	e.ReturnType == context.GetTypeSymbol(SpecialType.System_Boolean) &&
	e.Parameters[0].Type == context.GetTypeSymbol(SpecialType.System_Object));
	typeArg = typeArg.BaseType;
	}
	}
	}
	IConstantValue constantValue = new ConstantValue<bool>(isUserDefinedTypeWithEquals);
	createdInvocation = new BoundConstantInvocationExpression(node, constantValue, context.GetTypeSymbol(SpecialType.System_Boolean));
	return true;
	}

UdonSharpBehaviour TypeSymbol.BaseType is returning null on line 136.
Exception happens on line 139.