irc to mattermost segmentation violation crash

[metalcated]

Environment:

• OS: Ubuntu 18.04 LTS and RHEL 7

Additional context

[0000]  INFO main:         [setupLogger:matterbridge.go:104] Enabling debug logging.
[0000]  INFO main:         [main:matterbridge.go:44] Running version 1.24.0 65c7ac80
[0000]  INFO router:       [Start:gateway/router.go:66] Parsing gateway gateway
[0000]  INFO router:       [Start:gateway/router.go:75] Starting bridge: irc.linknet
[0000]  INFO irc:          [Connect:bridge/irc/irc.go:81] Connecting irc.link-net.nl:7000
[0000] DEBUG irc:          [getClient:bridge/irc/irc.go:306] setting pingdelay to 1m0s
[0000] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "CLIENT_INIT irc.link-net.nl:7000"
[0000] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "NOTICE AUTH :*** Looking up your hostname..."
[0000] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "NOTICE AUTH :*** Checking Ident"
[0000] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "NOTICE AUTH :*** Couldn't look up your hostname"
[0011] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "NOTICE AUTH :*** No Ident response"
[0011] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "PING FFFFFFFF4E901BF0"
[0011] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] ":irc.link-net.nl NOTICE botname :*** Your host is mangled by I-line. Congrats."
[0011] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] ":irc.link-net.nl 001 botname :Welcome to the LinkNet Internet Relay Chat Network botname!~botname@ipv6-address"
[0011] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "CLIENT_GENERAL_UPDATED"
[0011] DEBUG irc:          [handleNewConnection:bridge/irc/handlers.go:122] Registering callbacks
[0011] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "CLIENT_GENERAL_UPDATED"
[0011] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "CLIENT_GENERAL_UPDATED"
[0011] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "CLIENT_GENERAL_UPDATED"
[0011] DEBUG irc:          [handleOther:bridge/irc/handlers.go:171] "NOTICE irc.link-net.nl :Connected to irc.link-net.nl using SSL encryption version: TLSv1.2"
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0xaf8f08]

goroutine 83 [running]:
github.com/42wim/matterbridge/bridge/irc.(*Birc).skipPrivMsg(0xc0003d3020, {0x0, 0x0, {0xc07e5e464ce3fddd, 0x2a7ab82a3, 0x3b5fdc0}, {0xc000080c00, 0x6}, {0xc0000e5080, 0x2, ...}, ...})
        /go/src/github.com/42wim/matterbridge/bridge/irc/irc.go:365 +0xc8
github.com/42wim/matterbridge/bridge/irc.(*Birc).handlePrivMsg(0xc0003d3020, 0xc00008d040, {0x0, 0x0, {0xc07e5e464ce3fddd, 0x2a7ab82a3, 0x3b5fdc0}, {0xc000080c00, 0x6}, {0xc0000e5080, ...}, ...})
        /go/src/github.com/42wim/matterbridge/bridge/irc/handlers.go:185 +0xe5
github.com/42wim/matterbridge/bridge/irc.(*Birc).handleNotice(0xc0003d3020, 0x15, {0x0, 0x0, {0xc07e5e464ce3fddd, 0x2a7ab82a3, 0x3b5fdc0}, {0xc000080c00, 0x6}, {0xc0000e5080, ...}, ...})
        /go/src/github.com/42wim/matterbridge/bridge/irc/handlers.go:155 +0xf3
github.com/lrstanley/girc.HandlerFunc.Execute(0xc000175320, 0xc000080c00, {0x0, 0x0, {0xc07e5e464ce3fddd, 0x2a7ab82a3, 0x3b5fdc0}, {0xc000080c00, 0x6}, {0xc0000e5080, ...}, ...})
        /go/src/github.com/42wim/matterbridge/vendor/github.com/lrstanley/girc/handler.go:67 +0x45
github.com/lrstanley/girc.(*Caller).exec.func1.1()
        /go/src/github.com/42wim/matterbridge/vendor/github.com/lrstanley/girc/handler.go:220 +0x1f5
created by github.com/lrstanley/girc.(*Caller).exec.func1
        /go/src/github.com/42wim/matterbridge/vendor/github.com/lrstanley/girc/handler.go:215 +0x654