Fix crashes in testTerminalInterface

Certain user profiles crash here

   from /lib/x86_64-linux-gnu/libQt5Widgets.so.5
    this=0x5555557c8da0, name=..., visible=true)
    at src/konsole/src/session/SessionController.cpp:2206
    mode=1) at src/konsole/src/Screen.cpp:2395
    at src/konsole/src/Vt102Emulation.cpp:1071
    this=0x555555dc2a30, cc=7)

BUG: 473043

(cherry picked from commit 5bda5740)