fix: report failure when server fails to start (#23)

Exit with an error when the server startup reports an error. For example, when the server fails to bind to the provided port.

src/exporter.go

@@ -85,7 +85,7 @@ func main() {
 		log.Print("ready")
 
 		err := <-svrErr
-		log.Print(err)
+		log.Fatal(err)
 	}
 }