Fix linter errors

tap/source/handle_af_packet.go

@@ -52,7 +52,7 @@ func (h *afPacketHandle) SetBPF(expr string) (err error) {
 		}
 		bpfIns = append(bpfIns, bpfIns2)
 	}
-	h.capture.SetBPF(bpfIns)
+	err = h.capture.SetBPF(bpfIns)
 	return
 }
 

tap/source/handle_pcap.go

@@ -9,10 +9,8 @@ import (
 )
 
 type pcapHandle struct {
-	source        *gopacket.PacketSource
-	capture       *pcap.Handle
-	decoder       gopacket.Decoder
-	decodeOptions gopacket.DecodeOptions
+	source  *gopacket.PacketSource
+	capture *pcap.Handle
 }
 
 func (h *pcapHandle) NextPacket() (packet gopacket.Packet, err error) {

tap/source/tcp_packet_source.go

@@ -76,7 +76,7 @@ func newTcpPacketSource(name, filename string, interfaceName string,
 		logger.Log.Infof("Using AF_PACKET socket as the capture source")
 	}
 
-	decoder := gopacket.DecodersByLayerName[fmt.Sprintf("%s", layers.LinkTypeEthernet)]
+	decoder := gopacket.DecodersByLayerName[string(layers.LinkTypeEthernet)]
 	result.Handle.SetDecoder(decoder, behaviour.Lazy, true)
 
 	if behaviour.BpfFilter != "" {