[node] clearer sendPiece error handling in sender node

src/node/node.go

@@ -223,8 +223,8 @@ func (node *Node) Start() {
 			// and wait for it to be ready again
 			if node.State.AllowedToTransfer && node.TransferInfo.Ready {
 				err = sendPiece(file, node.Net.Conn, node.Net.EncryptionKey)
-				if err != nil {
-					if err == ErrorSentAll {
+				switch err {
+				case ErrorSentAll:
 					// the file has been sent fully
 					fileIDBuff := new(bytes.Buffer)
 					err = binary.Write(fileIDBuff, binary.BigEndian, file.ID)
@@ -253,13 +253,15 @@ func (node *Node) Start() {
 					})
 
 					node.State.Stopped = true
-					} else {
+
+				case nil:
+
+				default:
 					node.State.Stopped = true
 
-						fmt.Printf("An error occured when sending a piece of \"%s\": %s\n", file.Name, err)
+					fmt.Printf("An error occured while sending a piece of \"%s\": %s\n", file.Name, err)
 					panic(err)
 				}
-				}
 
 				node.TransferInfo.Ready = false
 			}