bandaid fix for Forge 1.20.1 UI crashing

common/src/main/java/com/seibel/distanthorizons/common/wrappers/world/ServerLevelWrapper.java

@@ -57,6 +57,7 @@ import java.nio.file.Path;
 #endif
 
 import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.Nullable;
 
 public class ServerLevelWrapper implements IServerLevelWrapper
 {
@@ -71,6 +72,9 @@ public class ServerLevelWrapper implements IServerLevelWrapper
 	@Deprecated // TODO circular references are bad
 	private IDhLevel parentDhLevel;
 	
+	@Nullable
+	private String worldFolderName = null;
+	
 	
 	
 	//==============//
@@ -115,12 +119,33 @@ public class ServerLevelWrapper implements IServerLevelWrapper
 	@Override
 	public String getWorldFolderName()
 	{
-		#if MC_VER >= MC_1_17_1
-		return this.level.getServer().getWorldScreenshotFile().get().getParent().getFileName().toString();
-		#else // <= 1.16.5
-		return this.level.getServer().getWorldScreenshotFile().getParentFile().getName();
-		#endif
+		// there's a bug with Forge 1.20.1 where the screenshot folder can be null
+		// hopefully the first time we get this it will be valid so any changes afterwards can be ignored
+		// TODO can we just replace this with getMcSaveFolder()? Why are we using the screenshot file anyway?
+		if (this.worldFolderName == null)
+		{
+			this.worldFolderName = this.tryGetWorldFolderName();
+		}
+		
+		return this.worldFolderName;
 	}
+	@Nullable
+	private String tryGetWorldFolderName()
+	{
+		try
+		{
+			#if MC_VER >= MC_1_17_1
+			return this.level.getServer().getWorldScreenshotFile().get().getParent().getFileName().toString();
+			#else // <= 1.16.5
+			return this.level.getServer().getWorldScreenshotFile().getParentFile().getName();
+			#endif
+		}
+		catch (Exception e)
+		{
+			return null;
+		}
+	}
+	
 	
 	@Override
 	public DimensionTypeWrapper getDimensionType() { return DimensionTypeWrapper.getDimensionTypeWrapper(this.level.dimensionType()); }