sensors: buildjson: add todo for failure

The daemon needs to validate the json configuration, either immediately
after it's parsed or when objects are built from it.

Change-Id: I52b5a558657ba1420bc4589de793cc496392f318
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/sensors/buildjson.cpp b/sensors/buildjson.cpp
index 7c4c7d6..4bf5ea7 100644
--- a/sensors/buildjson.cpp
+++ b/sensors/buildjson.cpp
@@ -79,6 +79,9 @@
     std::map<std::string, struct SensorConfig> config;
     auto sensors = data["sensors"];
 
+    /* TODO: If no sensors, this is invalid, and we should except here or during
+     * parsing.
+     */
     for (const auto& sensor : sensors)
     {
         config[sensor["name"]] = sensor.get<struct SensorConfig>();