The two classes called ConfigDict and FrozenConfigDict are "dict-like" data structures with dot access to nested elements. Together, they are supposed to be used as a main way of expressing ...
As more complex calculation and check inside ISR are introduced from v1.2.0, there is possibly some crash depending on use-case. You can modify to use larger HW_TIMER_INTERVAL_US, (from current 33.3uS ...