Fix null pointer in DataSourceHandler error handler

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

@@ -150,12 +150,16 @@ public abstract class AbstractDataSourceHandler
 				}
 				catch (DataCorruptedException e)
 				{
+					// there's a rare issue where the exception doesn't
+					// have a message, which can cause problems
+					String message = (e.getMessage() == null) ? e.getMessage() : "No Error message for exception ["+e.getClass().getSimpleName()+"]";
+					
 					// Only log each message type once.
 					// This is done to prevent logging "No compression mode with the value [2]" 10,000 times 
 					// if the user is migrating from a nightly build and used ZStd.
-					if (CORRUPT_DATA_ERRORS_LOGGED.add(e.getMessage()))
+					if (CORRUPT_DATA_ERRORS_LOGGED.add(message))
 					{
-						LOGGER.warn("Corrupted data found at pos [" + DhSectionPos.toString(pos) + "]. Data at position will be deleted so it can be re-generated to prevent issues. Future errors with this same message won't be logged. Error: [" + e.getMessage() + "].", e);
+						LOGGER.warn("Corrupted data found at pos [" + DhSectionPos.toString(pos) + "]. Data at position will be deleted so it can be re-generated to prevent issues. Future errors with this same message won't be logged. Error: [" + message + "].", e);
 					}
 					
 					this.repo.deleteWithKey(pos);
@@ -163,9 +167,6 @@ public abstract class AbstractDataSourceHandler
 			}
 			else
 			{
-				// TODO does this need any special logic to be populated from the existing DTOs?
-				//  and/or is that necessary?
-				//  Everything already appears to be populating correctly.
 				dataSource = this.makeEmptyDataSource(pos);
 			}
 		}