GTK+ dialogs always crash

[slajerek]

Compilation Environment

• OS (eg: OSX 10.14, Ubuntu 18.04): assertion failed #1 SMP Debian 5.10.70-1 (2021-09-30)
• Compiler (eg: GCC, Clang): gcc
• Compiler Version (eg: MSVC 2017): gcc version 10.2.1 20210110 (Debian 10.2.1-6)
• Build directory used (eg: build/gmake_linux: included sources
• Have I attempted to reproduce the problem on the devel branch? No, devel does not compile

Describe the bug

GTK+ always crashes on any file dialog operation:

libpng warning: Image width exceeds user limit in IHDR
libpng warning: Image height exceeds user limit in IHDR
libpng error: Invalid IHDR data
Segmentation fault

Additional context

Note, the app that uses NFD is using SDL2 only and might be that GTK+ is not initialised. Devel branch does not compile with errors like

ftg_core.h:13771:12: error: stray ‘\342’ in program
13771 |     You can’t perform that action at this time.

User Description

Open source / Individual.