Arch Linux

Description:
When selecting the "Transform a layer of a selection" tool while having an image opened and then switching to another tool, krita crashes with signal 6 (ABRT).

Additional info:
* extra/krita 4.2.8.2-1

Steps to reproduce:
1. start krita
2. open file or create a new one
3. select "Transform a layer of a selection" (Ctrl+T) tool
4. select some other tool e.g. Move Tool (T)
5. crash

last log msg before crash:

krita: /usr/include/boost/optional/optional.hpp:1207: boost::optional<T>::reference_type boost::optional<T>::get() [with T = ToolTransformArgs; boost::optional<T>::reference_type = ToolTransformArgs&]: Assertion `this->is_initialized()' failed.
Aborted (core dumped)

gdb bt:
#0 0x00007f8b4528af25 in raise () from /usr/lib/libc.so.6
#1 0x00007f8b45274897 in abort () from /usr/lib/libc.so.6
#2 0x00007f8b45274767 in __assert_fail_base.cold () from /usr/lib/libc.so.6
#3 0x00007f8b45283526 in __assert_fail () from /usr/lib/libc.so.6
#4 0x00007f8b3435e124 in ?? () from /usr/lib/kritaplugins/kritatooltransform.so
#5 0x00007f8b3435fb7e in ?? () from /usr/lib/kritaplugins/kritatooltransform.so
#6 0x00007f8b46b22705 in ?? () from /usr/lib/libkritaimage.so.18
#7 0x00007f8b456df922 in ?? () from /usr/lib/libQt5Core.so.5
#8 0x00007f8b456dc530 in ?? () from /usr/lib/libQt5Core.so.5
#9 0x00007f8b4344e4cf in start_thread () from /usr/lib/libpthread.so.0
#10 0x00007f8b4534e2d3 in clone () from /usr/lib/libc.so.6