MessageInputTextView: Fix GTK warning when closing chat control

Fixes #10146
3 jobs for master in 4 minutes and 27 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #18954
run-appdata

00:00:07

passed #18953
run-tests

00:04:04

 
  Build
passed #18955
run-build

00:00:15