Issue when compiling main in SwiftMocksClient

[nicofrancken]

When compiling the source code I sometimes get the error: "Cannot convert value of type 'String' to closure result type 'Int' (see attached screenshot)

It seems to mixup the InputType and ReturnType generic parameter. If I look at the source code I cannot explain why this is happening. Do you have the same? Do you have any explanation what causes this?

I'm currently in the process of adding async and throwable support to this framework but this bug keeps me from completing the PR.