C#

[OperationContract]
[FaultContract(typeof(RemoteException))]
Task SetInfraredFocus(string _clientName, double _focus);

public void SetFocus(double _focus)
{
    try
    {
        m_RemoteManualPsControl.SetInfraredFocus(UtilsEnvironment.TerminalName, _focus).Wait();
    }
    catch (Exception ex)
    {
        Logger.LogException(Name, ex);
    }
}

public Task SetInfraredFocus(string _clientName, double _focus)
{
    Task task = new Task(() => RemoteChannelProvider.Call(_channel => _channel.SetInfraredFocus(_clientName, _focus)));
    task.Start();
    return task;
}

public async Task SetInfraredFocus(string _clientName, double _focus)
{
    try
    {
        await Task.Delay(1);
        throw new Exception("Oh f***!");
    }
    catch (Exception ex)
    {
        Logger.LogException(Name, ex);
        RemoteException.ThrowFaultExceptionFromException(ex);
    }
}

Quote:

Any time you find yourself switching on a type in a generic you are almost certainly doing something wrong. Generics should be generic; they should operate identically completely independent of the type.

If T can only be int or string then don't write your code this way at all in the first place. Write two methods, one that returns an int and one that returns a string.

// 'KeyType has been set in the class initializer

public TKey GetNextKey(TKey key = default(TKey))
{
    if (! KeysUsed.Contains(key))
    {
        CurrentKey = key;
        KeysUsed.Add(key);
        return key;
    }
    
    switch (KeyType)
    {
        case Type _ when KeyType == typeof(Int32):
            int i = (Int32) (object) key + 1;
            CurrentKey = (TKey)(object) i;
            break;
        case Type _ when KeyType == typeof(string):  // incomplete
            string s = (string) (object) key;
            s += GetAGuid(); // code not shown here
            CurrentKey = (TKey)(object)s;
            break;

        default:
            throw new ArgumentException("unsupported TKey Type");
    }

    KeysUsed.Add(CurrentKey);
    return CurrentKey;
}

/*
		{"volunteer":
			{
				"id":16838,
//
// other properties successfully deserialized
//
                "roles":[           // this array deserialized successfully
                    {
                        "id":1613,
                        "name":"3Rings Administrator",
                        "suffix":null
                    },
                    {
                        "id":9707,
                        "name":"Mentor",
                        "suffix":""
                    },
                    {
                        "id":1612,
                        "name":"Everyone",
                        "suffix":null
                    }
                ],
                "volunteer_properties":[  // this array not deserialized
                    {
                        "first_name":{
                            "id":3990,
                            "org_name":"First Name",
                            "value":"Richard"
                        }
                    },
                    {"surname":{"id":3991,"org_name":"Surname","value":"MacCutchan "}},
//
// a number of other entries in the same form
//
                ]
			}
		}
*/

//
// the relevant DataContract classes
//
	[DataContract]
	internal class Role		// role items all deserialized successfully
    {
		[DataMember]
		internal int id;
		[DataMember]
		internal string name;
		[DataMember]
		internal string suffix;
	}

    [DataContract]
	internal class Property
    {
		[DataMember]
		internal int id;
		[DataMember]
		internal string org_name;
		[DataMember]
		internal string value;
	}


    [DataContract]
    internal class Propentry
    {
        [DataMember]
        internal Property property;
    }
    [DataContract]
    internal class Properties
    {
        [DataMember]
        internal Propentry propentry;
    }

	// each item contains a number of properties
    [DataContract]
	internal class Volunteer
	{
		[DataMember]
		internal int id;
//
// other members all deserialized successfully
//
		[DataMember]
		internal Role[] roles;
        [DataMember]
        internal Propentry[] volunteer_properties;

    }

	// the main array of items
    [DataContract]
	internal class VolList
	{
		[DataMember]
		internal Volunteer[] volunteers;
	}