If something within BLELocalDevice::begin() fail calls to end will fault

[KurtE]

In the case that I was debugging, I am testing running the library on top of the USBHost_t36 code on Teensy 3.6 or 4.x.

It works with some Bluetooth dongles and not others. In the case I am debugging it faults when I use a CSR 4.0 dongle.

I traced it to the call:

  if (HCI.setLeEventMask(0x00000000000003FF) != 0) {
    end();
    return 0;
  }

It failed with error code 0x12.

The call to end() ends up faulting.

The reason GATT.begin();
has not been called. It is called near the end of the BLELocalDevice::begin() ,

And BLELocalDevice::end() calls GATT.end.

void BLELocalDevice::end()
{
  GATT.end();
...

And GAT.end() calls off and deletes objects which have not yet been created.

void GATTClass::end()
{
  if (_genericAccessService->release() == 0)
    delete(_genericAccessService);
  
  if (_deviceNameCharacteristic->release() == 0)
    delete(_deviceNameCharacteristic);
  
  if (_appearanceCharacteristic->release() == 0)
    delete(_appearanceCharacteristic);
  
  if (_genericAttributeService->release() == 0)
    delete(_genericAttributeService);
  
  if (_servicesChangedCharacteristic->release() == 0)
    delete(_servicesChangedCharacteristic);
  
  clearAttributes();
}

Possible fixes:

1. Don't call GATT.end() if begin has not yet been called.
2. Change the GATT code to check before calling...
   like:

  if (_genericAccessService && (_genericAccessService->release() == 0))
    delete(_genericAccessService);

Wondering if is the same issue, that is mentioned in #273