Update PuttySessionsRegistryProvider.cs

remove unreachable code
- no need to test for null, PuttySessionsKey is a const with a value set on instantiation

mRemoteNG/Config/Putty/PuttySessionsRegistryProvider.cs

@@ -24,8 +24,6 @@ namespace mRemoteNG.Config.Putty
 
         public override string[] GetSessionNames(bool raw = false)
         {
-            if (PuttySessionsKey == null) return null;
-
             var sessionsKey = Registry.CurrentUser.OpenSubKey(PuttySessionsKey);
             if (sessionsKey == null) return new string[] { };