I use flightgear 2019.1 on archlinux.
If flightgear has been launched from commande line without the use of Qt5 launcher (no option --launcher), then if the user clicks on the menu "file --> reset" then flightgear will crash with this message :
malloc(): invalid size (unsorted)
Abandon
The bug doesn't occur if flightgear is launched with the Qt5 launcher (fgfs --launcher),
the version of Qt5 used : 5.14.0
Thanks for the report, will add it to my backlog (which is unfortunately rather long...)
Correction : the bug occurs also even if flightgear has been launched with Qt5 launcher, with the same error message :
malloc(): invalid size (unsorted)
Abandon
Wild guess: this is a duplicate of: https://sourceforge.net/p/flightgear/codetickets/2127/