Okay so two things: I still cannot reproduce a crash and the code is quite complex. Can you upload your whole current project to Github?
And: The Arduino-ESP32 core in the 1.0.6 version that PlatformIO uses has a bug regarding timers per Hardware timer issue with ESP32 - #11 by maxgerhardt in which they won’t fire correctly. To make timers work reliably I had to add volatile in esp32-hal-timer.c per Timer functions do not work at all in PlatformIO · Issue #5337 · espressif/arduino-esp32 · GitHub and change
the last argument of that line to false.