Error World Map already exists! Maybe it's an outdated SlimeWorld object?

[ProtoGhost]

Describe the issue
I can't load a world from version 1.1.1 of the plugin
Spigot version
git-PaperSpigot-2894af04d (MC: 1.8.8)
Plugin version
v2.3.0-SNAPSHOT
How to reproduce
Try load that was used in the old version of the plugin
Crash reports (if available)
Nothing in the Console only thing:
"SWM >> Failed to generate world: World already exists! Maybe it's an outdated SlimeWorld object?."