add currWireError to I2C sensor

Author: padok

src/sensors/MagneticSensorI2C.cpp

@@ -95,7 +95,7 @@ int MagneticSensorI2C::read(uint8_t angle_reg_msb) {
   // notify the device that is aboout to be read
 	wire->beginTransmission(chip_address);
 	wire->write(angle_reg_msb);
-  wire->endTransmission(false);
+  currWireError = wire->endTransmission(false);
 
   // read the data msb and lsb
 	wire->requestFrom(chip_address, (uint8_t)2);

src/sensors/MagneticSensorI2C.h

@@ -51,6 +51,9 @@ class MagneticSensorI2C: public Sensor{
     /** experimental function to check and fix SDA locked LOW issues */
     int checkBus(byte sda_pin , byte scl_pin );
 
+    /** current error code from Wire endTransmission() call **/
+    uint8_t currWireError = 0;
+
   private:
     float cpr; //!< Maximum range of the magnetic sensor
     uint16_t lsb_used; //!< Number of bits used in LSB register