Add a couple full data source null checks

core/src/main/java/com/seibel/distanthorizons/core/dataObjects/fullData/sources/FullDataSourceV2.java

@@ -37,6 +37,7 @@ import com.seibel.distanthorizons.core.wrapperInterfaces.chunk.IChunkWrapper;
 import com.seibel.distanthorizons.coreapi.ModInfo;
 import it.unimi.dsi.fastutil.longs.LongArrayList;
 import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.NotNull;
 
 import javax.annotation.Nullable;
 import java.util.Arrays;
@@ -223,8 +224,8 @@ public class FullDataSourceV2 implements IDataSource<IDhLevel>
 	public LongArrayList get(int relX, int relZ) throws IndexOutOfBoundsException { return this.dataPoints[relativePosToIndex(relX, relZ)]; }
 	
 	@Override
-	public boolean update(FullDataSourceV2 inputDataSource, @Nullable IDhLevel level) { return this.update(inputDataSource); }
-	public boolean update(FullDataSourceV2 inputDataSource)
+	public boolean update(@NotNull FullDataSourceV2 inputDataSource, @Nullable IDhLevel level) { return this.update(inputDataSource); }
+	public boolean update(@NotNull FullDataSourceV2 inputDataSource)
 	{
 		byte thisDetailLevel = this.pos.getDetailLevel();
 		byte inputDetailLevel = inputDataSource.pos.getDetailLevel();

core/src/main/java/com/seibel/distanthorizons/core/file/AbstractNewDataSourceHandler.java

@@ -11,6 +11,7 @@ import com.seibel.distanthorizons.core.util.LodUtil;
 import com.seibel.distanthorizons.core.util.threading.PositionalLockProvider;
 import com.seibel.distanthorizons.core.util.threading.ThreadPoolUtil;
 import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.File;
@@ -110,7 +111,7 @@ public abstract class AbstractNewDataSourceHandler
 	
 	/**
 	 * Returns the {@link TDataSource} for the given section position. <Br>
-	 * The returned data source may be null if there was a problem. <Br> <Br>
+	 * The returned data source may be null if repo is in the process of shutting down. <Br> <Br>
 	 *
 	 * This call is concurrent. I.e. it supports being called by multiple threads at the same time.
 	 */
@@ -135,9 +136,10 @@ public abstract class AbstractNewDataSourceHandler
 	}
 	/**
 	 * Should only be used in internal file handler methods where we are already running on a file handler thread.
-	 * Shouldn't return null.
+	 * Can return null if the repo is in the process of being shut down
 	 * @see AbstractNewDataSourceHandler#getAsync(DhSectionPos)
 	 */
+	@Nullable
 	public TDataSource get(DhSectionPos pos)
 	{
 		TDataSource dataSource = null;
@@ -170,7 +172,7 @@ public abstract class AbstractNewDataSourceHandler
 	// data updating //
 	//===============//
 	
-	public CompletableFuture<Void> updateDataSourceAsync(FullDataSourceV2 inputDataSource)
+	public CompletableFuture<Void> updateDataSourceAsync(@NotNull FullDataSourceV2 inputDataSource)
 	{
 		ThreadPoolExecutor executor = ThreadPoolUtil.getUpdatePropagatorExecutor();
 		if (executor == null || executor.isTerminated())
@@ -211,7 +213,7 @@ public abstract class AbstractNewDataSourceHandler
 	 * After this method returns the inputData will be written to file.
 	 * @param updatePos the position to update 
 	 */
-	protected void updateDataSourceAtPos(DhSectionPos updatePos, FullDataSourceV2 inputData, boolean lockOnUpdatePos)
+	protected void updateDataSourceAtPos(DhSectionPos updatePos, @NotNull FullDataSourceV2 inputData, boolean lockOnUpdatePos)
 	{
 		boolean methodLocked = false;
 		// a lock is necessary to prevent two threads from writing to the same position at once,

core/src/main/java/com/seibel/distanthorizons/core/file/fullDatafile/FullDataSourceProviderV2.java

@@ -250,8 +250,11 @@ public class FullDataSourceProviderV2
 												
 												try (FullDataSourceV2 dataSource = this.get(childPos))
 												{
-													this.updateDataSourceAtPos(parentUpdatePos, dataSource, false);
-													this.repo.setApplyToParent(childPos, false);
+													if (dataSource != null) // can return null when the file handler is being shut down
+													{
+														this.updateDataSourceAtPos(parentUpdatePos, dataSource, false);
+														this.repo.setApplyToParent(childPos, false);
+													}
 												}
 											}
 											catch (Exception e)

core/src/main/java/com/seibel/distanthorizons/core/render/LodRenderSection.java

@@ -138,6 +138,12 @@ public class LodRenderSection implements IDebugRenderable, AutoCloseable
 			{
 				// get this positions data source
 				fullDataSource = this.fullDataSourceProvider.get(this.pos);
+				if (fullDataSource == null)
+				{
+					// the file handler is being shut down, we won't be rendering anything anyway
+					return;
+				}
+				
 				renderSource = FullDataToRenderDataTransformer.transformFullDataToRenderSource(fullDataSource, this.level);
 				if (renderSource.isEmpty())
 				{