It looks like the game's running out of memory when it's saving.
You could try upping the amount of memory that the game can use - open the "config.json" file in the same folder as the exe. It should look like this:
{
"classPath": [
"game/desktop-1.0.jar"
],
"mainClass": "com.cairn4.moonbase.desktop.DesktopLauncher",
"vmArgs": [
"-Xmx1G"
]
}The line "-Xmx1G" is the max Java heap size (1 GB) - you can try increasing that to see it it runs smoother and crashes less often. Like to set the max to 4 GB, make it say "- Xmx4G"