bug#49940: IceCat crashes when attempting to activate 'reader view' via shortcut

[Maxim Cournoyer]

Hello,

I can reproduce this for some time, currently using IceCat
78.12.0-guix0-preview1.

Repro:

1. Open a web page in IceCat.
2. Press the 'Control + Alt + r' keys altogether to enable the 'reader
view' mode.
3. Observe a crash.

Thank you,

Maxim