Handle collector Start error

[albertteoh]

Signed-off-by: albertteoh albert.teoh@logz.io

Which problem is this PR solving?

• Fixes Jaeger collector not reporting "bind address already in use" error #2640

Short description of the changes

• Handle error from Start call in collector.
• Fixes symptom of collector not reporting error and exiting if port 14250 is taken.

Testing

Tested happy path where no port conflicts exist as well as failure case:

• Start jaeger all-in-one
• Logs error and returns non-0 exit status code:

$ SPAN_STORAGE_TYPE=memory go run ./cmd/collector/main.go
...
{"level":"fatal","ts":1606280888.116083,"caller":"collector/main.go:100","msg":"Failed to start collector","error":"could not start gRPC collector failed to listen on gRPC port: listen tcp :14250: bind: address already in use","stacktrace":"main.main.func1\n\t/Users/albertteoh/go/src/github.com/albertteoh/jaeger/cmd/collector/main.go:100\ngithub.com/spf13/cobra.(*Command).execute\n\t/Users/albertteoh/go/pkg/mod/github.com/spf13/cobra@v0.0.5/command.go:826\ngithub.com/spf13/cobra.(*Command).ExecuteC\n\t/Users/albertteoh/go/pkg/mod/github.com/spf13/cobra@v0.0.5/command.go:914\ngithub.com/spf13/cobra.(*Command).Execute\n\t/Users/albertteoh/go/pkg/mod/github.com/spf13/cobra@v0.0.5/command.go:864\nmain.main\n\t/Users/albertteoh/go/src/github.com/albertteoh/jaeger/cmd/collector/main.go:135\nruntime.main\n\t/usr/local/Cellar/go/1.15.2/libexec/src/runtime/proc.go:204"}
exit status 1