Added nullptr check in EmotibitEda_cpp

[nitin710]

Description

• Added nullptr checks. These were causing a crash on the agave board.

Requirements

• None

Issues Referenced

• Fixes #293

Documentation update

• None

Testing

• This is a minor patch, so there is no test added in the Feature test protocol doc.
  • In the future, when we do implement a mechanism of "selectively setting up sensors", we will probably add a test to check that the fw does not crash if using a sensors module not setup
• For now, i just test it by bypassing eda setup in the setup()

  // Setup EDA
  #if(0) // #if defined out
  {
  Serial.println("\nInitializing EDA... ");
  if (emotibitEda.setup(_hwVersion, _samplingRates.eda / ((float)_samplesAveraged.eda), &eda, &edl, &edr, _EmotiBit_i2c, &edlBuffer, &edrBuffer))
  {
      EmotiBitFactoryTest::updateOutputString(factoryTestSerialOutput, EmotiBitFactoryTest::TypeTag::ADC_INIT, EmotiBitFactoryTest::TypeTag::TEST_PASS);
      Serial.println("Completed");
  }
  else
  {
      EmotiBitFactoryTest::updateOutputString(factoryTestSerialOutput, EmotiBitFactoryTest::TypeTag::ADC_INIT, EmotiBitFactoryTest::TypeTag::TEST_FAIL);
      Serial.println(factoryTestSerialOutput);
      Serial.println("failed");
  }
  }
  Serial.println("\nLoading EDA calibration... ");
  if (emotibitEda.stageCalibLoad(&_emotibitNvmController, true))
  {
      Serial.println("Completed");
  }
  else
  {
      Serial.println("failed");
  }
  #endif

  and the oscilloscope continued set up and continued normal function + recording without eda (which was previously crashing for the agave board)

[nitin710]

Changes made, as requested.

[produceconsumerobot]

@nitin710 Looks good