lib/api: Missing error handling in API delete-device (#7494)

lib/api/confighandler.go

@@ -187,6 +187,10 @@ func (c *configMuxBuilder) registerDevice(path string) {
 
 	c.Handle(http.MethodDelete, path, func(w http.ResponseWriter, _ *http.Request, p httprouter.Params) {
 		id, err := protocol.DeviceIDFromString(p.ByName("id"))
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
 		waiter, err := c.cfg.RemoveDevice(id)
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusBadRequest)