public Profile GetProfile(string name) {
    if (string.IsNullOrEmpty(name)) throw new ArgumentException($"name cannot be null");
    var profile = Profiles.SingleOrDefault(o => o.Name == name);
    if (profile == null) throw new ArgumentException($"Could not find profile for {name}");
    return profile;
}

public Profile GetProfile(string name) => 
	string.IsNullOrEmpty(name) ? throw new ArgumentException($"name cannot be empty or null") :
        Profiles.SingleOrDefault(o => o.Name == name) 
            ?? throw new ArgumentException($"Could not find profile for {name}");

public class Profile 
{
	public string Name { get; set; }
	public string SomeProp { get; set; }
}

List<Profile> Profiles = new List<Profile> {
	new Profile { Name = "Jeffrey" },
	new Profile { Name = "darkthread" }
};

public Profile GetProfile(string name) => 
	string.IsNullOrEmpty(name) ? throw new ArgumentException($"name cannot be empty or null") :
    Profiles.SingleOrDefault(o => o.Name == name) 
    ?? throw new ArgumentException($"Could not find profile for {name}");

void Main()
{
	Action<string> test = (name) => {
		try 
		{
			var p = GetProfile(name);	
			Console.WriteLine($"PASS - {p.Name}");
		}
		catch (Exception ex) {
			Console.WriteLine($"ERR - {name} / {ex.Message}");
		}
	};
	test(null);
	test(string.Empty);
	test("NoSuchProfile");
	test("Jeffrey");
}