Replace Color plugin fails

Steps to reproduce

• Open Glaxnimate
• Open plugin Replace color
• Select color to replace
• Select new color
• Select OK
• Plugin returns an error - plugin raised an exception.

Result

Expected result would be to have the color replaced.

Version

Glaxnimate: 0.5.4+deb- dc26f367 System: Linux Mint 21.3 Kernel: linux 5.15.0-105-generic CPU: x86_64 Application Qt: 5.15.3 System Qt: 5.15.3 ZLib: 1.2.11 Potrace: potracelib 1.16 Libav: Lavu56.70.100, Lavf58.76.100, Lavc58.134.100, SwS5.9.100 libarchive: 3.6.0