esp-wifi: Possible footgun when initializing

[bjoernQ]

On Matrix a user reported a case where calling new_with_mode got stuck (https://matrix.to/#/!LdaNPfUfvefOLewEIM:matrix.org/$Twxz-4_dqbWmhn3qiXD-qUYLScmE3Nk62QFclcB7eTY)

The reason is that the user's code called it inside a locked critical_section::Mutex and WiFi wasn't initialized, yet. The function will call wifi_init which calls into the WiFi drivers. There it tried to take a semaphore which is to be given by the WiFi task.

semaphore_take will see the locked semaphore and try to yield (i.e. to let some other task make progress und unlock it). Since we are inside a critical-section this cannot work

We should

• document that behavior
• assert or at least error-log when yield is tried with interrupts disabled (was already suggested before)