Fix calling of IMU/MAG data when no new data available

esp32/include/peripherals/imu.h

@@ -88,6 +88,8 @@ class IMU : public SensorBase<IMUAnglesMsg> {
         if (_imu->dataReady())
         {
             _imu->getAGMT();
+        } else {
+            return false;
         }
         #endif
         _msg.rpy[0] = _imu->accX();

esp32/include/peripherals/magnetometer.h

@@ -48,6 +48,8 @@ class Magnetometer : public SensorBase<MagnetometerMsg> {
         if (_imu->dataReady())
         { 
             _imu->getAGMT();
+        } else {
+            return false;
         }
         #endif
         _msg.rpy[0] = _mag->magX();