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 10uS), ...
Crumbuino-Nano corresponds to our popular Crumb328 V2.3 module with the ATmega328P mikrocontroller and CP2102 USB UART converter. As Crumbuino-Nano version the module comes with Arduino bootloader ...