Fix #8 assign to nil map

Dockerfile

@@ -3,7 +3,7 @@ FROM golang:1.12-rc-alpine as build
 RUN apk add --no-cache git=2.20.1-r0
 
 WORKDIR /src
-COPY go.mod go.sum .env *.go iceservers.txt ./
+COPY go.mod go.sum .env *.go ./
 COPY backend-protobuf/go ./backend-protobuf/go
 RUN go get -d -v ./...
 RUN CGO_ENABLED=0 go build -ldflags "-s -w"

main.go

@@ -230,6 +230,10 @@ func NewConnection(w http.ResponseWriter, r *http.Request, p httprouter.Params)
 		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 		return
 	}
+
+  if _, ok := userTracks[user.UserId]; !ok {
+    userTracks[user.UserId] = make(map[string]*webrtc.Track)
+  }
 	userTracks[user.UserId][user.ClientId] = track
 
 	// Do signalling things