Assert fails on empty string

[dimmykar]

I'm trying to port my code from v1.2.0 to v2.1.0, which is integrated into the coreMQTT-Agent. However, I have come across an unexpected assertion firing which was not present in previous v1.2.0. Upon analyzing the code, I discovered that the problem also exists in v2.1.1 too.

coreMQTT/source/core_mqtt.c

Line 1869 in b0acf49

assert( ( length != 0U ) == ( string != NULL ) );

In my code I am trying to connect to a test broker that does not require a login and password. That's why I pass empty strings as "" and not NULL. strlen of the empty string returns 0, so this assertion fires: I have a valid string that is not NULL, but its length is 0.

Workaround of this problem can be achieved by passing a pointer to NULL instead of the empty string "". But still I think this case should not be handled as fatal error.

[archigup]

Thanks for the bug report! I'll open a PR to fix this shortly.