AP_InertialSensor: check for NULL device pointer in probe()

handle missing devices

libraries/AP_InertialSensor/AP_InertialSensor_BMI160.cpp

@@ -131,6 +131,9 @@ AP_InertialSensor_Backend *
 AP_InertialSensor_BMI160::probe(AP_InertialSensor &imu,
                                 AP_HAL::OwnPtr<AP_HAL::SPIDevice> dev)
 {
+    if (!dev) {
+        return nullptr;
+    }
     auto sensor = new AP_InertialSensor_BMI160(imu, std::move(dev));
 
     if (!sensor) {

libraries/AP_InertialSensor/AP_InertialSensor_L3G4200D.cpp

@@ -107,6 +107,9 @@ AP_InertialSensor_L3G4200D::~AP_InertialSensor_L3G4200D()
 AP_InertialSensor_Backend *AP_InertialSensor_L3G4200D::probe(AP_InertialSensor &imu,
                                                              AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev)
 {
+    if (!dev) {
+        return nullptr;
+    }
     AP_InertialSensor_L3G4200D *sensor
         = new AP_InertialSensor_L3G4200D(imu, std::move(dev));
     if (!sensor || !sensor->_init_sensor()) {

libraries/AP_InertialSensor/AP_InertialSensor_LSM9DS0.cpp

@@ -397,6 +397,9 @@ AP_InertialSensor_Backend *AP_InertialSensor_LSM9DS0::probe(AP_InertialSensor &_
                                                             AP_HAL::OwnPtr<AP_HAL::SPIDevice> dev_accel,
                                                             enum Rotation rotation)
 {
+    if (!dev_gyro || !dev_accel) {
+        return nullptr;
+    }
     AP_InertialSensor_LSM9DS0 *sensor =
         new AP_InertialSensor_LSM9DS0(_imu, std::move(dev_gyro), std::move(dev_accel),
                                       LSM9DS0_DRY_X_PIN, LSM9DS0_DRY_G_PIN,

libraries/AP_InertialSensor/AP_InertialSensor_MPU6000.cpp

@@ -261,6 +261,9 @@ AP_InertialSensor_Backend *AP_InertialSensor_MPU6000::probe(AP_InertialSensor &i
                                                             AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                                             enum Rotation rotation)
 {
+    if (!dev) {
+        return nullptr;
+    }
     AP_InertialSensor_MPU6000 *sensor =
         new AP_InertialSensor_MPU6000(imu, std::move(dev), true, rotation);
     if (!sensor || !sensor->_init()) {

libraries/AP_InertialSensor/AP_InertialSensor_MPU9250.cpp

@@ -217,6 +217,9 @@ AP_InertialSensor_Backend *AP_InertialSensor_MPU9250::probe(AP_InertialSensor &i
                                                             AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev,
                                                             enum Rotation rotation)
 {
+    if (!dev) {
+        return nullptr;
+    }
     AP_InertialSensor_MPU9250 *sensor =
         new AP_InertialSensor_MPU9250(imu, std::move(dev), rotation);
     if (!sensor || !sensor->_init()) {
@@ -233,6 +236,9 @@ AP_InertialSensor_Backend *AP_InertialSensor_MPU9250::probe(AP_InertialSensor &i
                                                             AP_HAL::OwnPtr<AP_HAL::SPIDevice> dev,
                                                             enum Rotation rotation)
 {
+    if (!dev) {
+        return nullptr;
+    }
     AP_InertialSensor_MPU9250 *sensor;
 
     dev->set_read_flag(0x80);