Fix EV3 sensor mode count decoding

It turns out that the underlying problem was that the sensor sends
the number of modes minus one and the code here did not account for it.

micropython/modules/ev3_sensors/ev3_sensor.c

@@ -301,7 +301,7 @@ bool ev3_sensor_describe_data(ev3_sensor *link, uint mode, data_miniinfo *out) {
     return false;
   }
   ev3_lock();
-  if (mode <= link->sensor_metadata.mode_count) {
+  if (mode < link->sensor_metadata.mode_count) {
     sensor_mode *mode_info = &link->sensor_metadata.modes[mode];
     out->format = mode_info->format;
     out->num_values = mode_info->values;

micropython/modules/ev3_sensors/sensor_info.c

@@ -54,26 +54,26 @@ void sensor_info_update(sensor_info *info, const uint8_t *msg, size_t len) {
         return;
       }
 
-      info->mode_count = parsed.mode_count;
+      info->mode_count = parsed.mode_count + 1;
       if (info->mode_count > MAX_SENSOR_MODE_COUNT) {
         info->mode_count = MAX_SENSOR_MODE_COUNT;
       }
 
 #if FULL_TYPEDATA
-      info->visible_mode_count = parsed.visible_mode_count;
+      info->visible_mode_count = parsed.visible_mode_count + 1;
       if (info->visible_mode_count > MAX_SENSOR_MODE_COUNT) {
         info->visible_mode_count = MAX_SENSOR_MODE_COUNT;
       }
 #endif
 
-      for (int i = 0; i <= info->mode_count; i++) {
+      for (int i = 0; i < info->mode_count; i++) {
         sensor_mode_init(&info->modes[i]);
       }
     }
   } else if (mtype == MTYPE_INFO) {
     require_at_least_bytes(len, 2);
     unsigned int mode_no = subtype_of_message(msg[0]);
-    if (mode_no <= info->mode_count) {
+    if (mode_no < info->mode_count) {
       sensor_mode_update(&info->modes[mode_no], msg, len);
     }
   }