Folderwatcher access to Application::_instance before initialisation

[sentry]

Sentry Issue: DESKTOP-WIN-AND-MAC-EVM

SIGABRT / 0xfffffffa / 0x3e80001743c: Fatal Error: SIGABRT / 0xfffffffa / 0x3e80001743c
  File "pthread_kill.c", line 44, in __pthread_kill_implementation
  File "pthread_kill.c", line 78, in __pthread_kill_internal
  File "pthread_kill.c", line 89, in pthread_kill
  File "malloc.c", line 3391, in __libc_free
  File "qobject.cpp", line 140, in QObjectData::~QObjectData

[sentry]

Sentry issue: DESKTOP-WIN-AND-MAC-EZV

[saw-jan]

How can we confirm the fix here?
CC @TheOneRing