time="2020-02-10T08:59:08Z" level=info msg="integration/mqtt: publishing message" ctx_id=9646ba10-4c29-4c8e-85dd-128d699a5a37 qos=0 topic=application/1/device/XXXXXXXXXXXXXXXX/join
time="2020-02-10T08:59:08Z" level=info msg="integration/postgresql: event stored" ctx_id=9646ba10-4c29-4c8e-85dd-128d699a5a37 dev_eui=a8404100018192ee event=join
time="2020-02-10T08:59:09Z" level=info msg="integration/mqtt: publishing message" ctx_id=9646ba10-4c29-4c8e-85dd-128d699a5a37 qos=0 topic=application/1/device/XXXXXXXXXXXXXXXX/rx
time="2020-02-10T08:59:09Z" level=info msg="integration/postgresql: event stored" ctx_id=9646ba10-4c29-4c8e-85dd-128d699a5a37 dev_eui=a8404100018192ee event=up
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xfbec3f]

goroutine 1432053 [running]:
github.com/Azure/azure-service-bus-go.(*Sender).Send(0xc000104770, 0x1718ca0, 0xc00017a040, 0xc0009d7ef0, 0x0, 0x0, 0x0, 0x0, 0x0)
        /go/pkg/mod/github.com/!azure/azure-service-bus-go@v0.10.0/sender.go:151 +0x34f
github.com/Azure/azure-service-bus-go.(*Queue).Send(0xc000544240, 0x1718ca0, 0xc00017a040, 0xc0009d7ef0, 0x0, 0x0)
        /go/pkg/mod/github.com/!azure/azure-service-bus-go@v0.10.0/queue.go:167 +0x1fc
github.com/brocaar/chirpstack-application-server/internal/integration/azureservicebus.(*Integration).publish(0xc0000e4150, 0x1718d60, 0xc0009c8840, 0x13d6411, 0x4, 0x1, 0xc0001daeb0, 0x8, 0x8, 0x170c8a0, ...)
        /chirpstack-application-server/internal/integration/azureservicebus/azure_service_bus.go:250 +0x784
github.com/brocaar/chirpstack-application-server/internal/integration/azureservicebus.(*Integration).publishRetry(0xc0000e4150, 0x1718d60, 0xc0009c8840, 0x13d6411, 0x4, 0x1, 0xc0001daeb0, 0x8, 0x8, 0x170c8a0, ...)
        /chirpstack-application-server/internal/integration/azureservicebus/azure_service_bus.go:212 +0x198
github.com/brocaar/chirpstack-application-server/internal/integration/azureservicebus.(*Integration).SendJoinNotification(0xc0000e4150, 0x1718d60, 0xc0009c8840, 0xc0009a8600, 0x1, 0xc000aa8700, 0x1c, 0xc0002c75d0, 0xa, 0xc0001daeb0, ...)
        /chirpstack-application-server/internal/integration/azureservicebus/azure_service_bus.go:69 +0xe1
github.com/brocaar/chirpstack-application-server/internal/integration/multi.(*Integration).SendJoinNotification.func1(0x1718d60, 0xc0009c8840, 0xc0009a8600, 0xc00029a630, 0x172c9e0, 0xc0000e4150)
        /chirpstack-application-server/internal/integration/multi/multi.go:108 +0xd2
created by github.com/brocaar/chirpstack-application-server/internal/integration/multi.(*Integration).SendJoinNotification
        /chirpstack-application-server/internal/integration/multi/multi.go:107 +0x100


[second example]

time="2020-02-17T18:53:07Z" level=info msg="integration/mqtt: publishing message" ctx_id=0a95d027-b3e8-4625-8e72-f699f05f3a7a qos=0 topic=application/2/device/XXXXXXXXXXXXXXXX/rx
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xfbec3f]

goroutine 4862466 [running]:
github.com/Azure/azure-service-bus-go.(*Sender).Send(0xc00010c690, 0x1718ca0, 0xc0001aa040, 0xc0012e5a40, 0x0, 0x0, 0x0, 0x0, 0x0)
        /go/pkg/mod/github.com/!azure/azure-service-bus-go@v0.10.0/sender.go:151 +0x34f
github.com/Azure/azure-service-bus-go.(*Queue).Send(0xc0004bae40, 0x1718ca0, 0xc0001aa040, 0xc0012e5a40, 0x0, 0x0)
        /go/pkg/mod/github.com/!azure/azure-service-bus-go@v0.10.0/queue.go:167 +0x1fc
github.com/brocaar/chirpstack-application-server/internal/integration/azureservicebus.(*Integration).publish(0xc0000fa000, 0x1718d60, 0xc000d7dce0, 0x13d5568, 0x2, 0x2, 0xc0000980b0, 0x8, 0x8, 0x170c9a0, ...)
        /chirpstack-application-server/internal/integration/azureservicebus/azure_service_bus.go:250 +0x784
github.com/brocaar/chirpstack-application-server/internal/integration/azureservicebus.(*Integration).publishRetry(0xc0000fa000, 0x1718d60, 0xc000d7dce0, 0x13d5568, 0x2, 0x2, 0xc0000980b0, 0x8, 0x8, 0x170c9a0, ...)
        /chirpstack-application-server/internal/integration/azureservicebus/azure_service_bus.go:212 +0x198
github.com/brocaar/chirpstack-application-server/internal/integration/azureservicebus.(*Integration).SendDataUp(0xc0000fa000, 0x1718d60, 0xc000d7dce0, 0xc000cb2750, 0x2, 0xc0004bef90, 0x10, 0xc0000be3c0, 0x14, 0xc0000980b0, ...)
        /chirpstack-application-server/internal/integration/azureservicebus/azure_service_bus.go:64 +0xdc
github.com/brocaar/chirpstack-application-server/internal/integration/multi.(*Integration).SendDataUp.func1(0x1718d60, 0xc000d7dce0, 0xc000cb2750, 0xc000a9cfc0, 0x172c9e0, 0xc0000fa000)
        /chirpstack-application-server/internal/integration/multi/multi.go:92 +0xb6
created by github.com/brocaar/chirpstack-application-server/internal/integration/multi.(*Integration).SendDataUp
        /chirpstack-application-server/internal/integration/multi/multi.go:91 +0xf1