Possibility to segmentation fault (mbed-os/hal/source/mbed_ticker_api.c)

[MariwanJ]

at line 244

static void set_handler(const ticker_data_t *const ticker, ticker_event_handler handler)
{
    ticker->queue->event_handler = handler;
}

The above code doesn't check if "queue" is defined.
There are many other places at the same file that assume the queue is defined which is quite bad.
The way queue is defined quite complicated and still I didn't figure out how it works. I am sub-classing TimerEvent and there is a possibility to get that variable with NULL pointer.
There must be a check before doing that. Code shouldn't compile.
It causes HARD_FAULT.

Tested with Nucleo-F207ZG