Using ? as a string literal inside a custom function stops highlighting

[Kurounin]

When using ? inside the body of a function the highlighting stops working (it's probably expecting an optional member access):

{{ func customFunc }}
private string _GetNullableValue(string? value, string defaultValue = string.Empty)
{
    return value ?? defaultValue;
}
{{ end }}

public partial class {{ Name }}
{
    {{ customFunc }}
}

Any idea on how to get around this? I can't put the func at the of the file or move it to a separate template file to include it.

[Kurounin]

I worked around the issue by moving the content of the function to a separate template file and then include the template, since including supports arguments as well, which I needed in my case.