fix offset in SendInternal for fragmented packets

Author: RevenantX

LiteNetLib/NetPeer.cs

@@ -566,7 +566,7 @@ private void SendInternal(
                     p.FragmentsTotal = (ushort)totalPackets;
                     p.MarkFragmented();
 
-                    Buffer.BlockCopy(data, partIdx * packetDataSize, p.RawData, NetConstants.FragmentedHeaderTotalSize, sendLength);
+                    Buffer.BlockCopy(data, start + partIdx * packetDataSize, p.RawData, NetConstants.FragmentedHeaderTotalSize, sendLength);
                     channel.AddToQueue(p);
 
                     length -= sendLength;