Merge pull request #3 from GTNewHorizons/fix-empty-blockarray

Fix crash when metadata array is empty

src/main/java/com/gtnewhorizons/postea/utility/ChunkFixerUtility.java

@@ -60,6 +60,15 @@ public class ChunkFixerUtility {
             // Blocks16 and Data16 exist only because of NEID.
             byte[] blockArray = section.getByteArray("Blocks16");
             byte[] metadataArray = section.getByteArray("Data16");
+            // If metadata array is empty, it was all zeroes. We create a new array to write our new values to,
+            // and only save this when a nonzero value was written
+            boolean wasAllZero = false;
+            if (metadataArray.length == 0) {
+                wasAllZero = true;
+                metadataArray = new byte[8192];
+            }
+            // Keep track of if we write a nonzero element to the metadata array
+            boolean hasWrittenNonZero = false;
 
             byte sectionY = section.getByte("Y");
 
@@ -84,6 +93,11 @@ public class ChunkFixerUtility {
                 blockConversionInfo.blockName = blockName;
                 blockConversionInfo.blockID = blockId;
                 blockConversionInfo.metadata = (byte) metadata; // Updated
+                // If we wrote a nonzero metadata, keep track of this because it means the
+                // new array needs to be written back to NBT
+                if (metadata != 0) {
+                    hasWrittenNonZero = true;
+                }
                 blockConversionInfo.world = world;
 
                 int x = index % 16;
@@ -107,6 +121,12 @@ public class ChunkFixerUtility {
                     metadataArray[index * 2 + 1] = (byte) (newMetadata & 0xFF);
                 }
             }
+
+            // After processing all replacements, if we made a new metadata array and wrote a nonzero value to it,
+            // write it back to world NBT to save
+            if (wasAllZero && hasWrittenNonZero) {
+                section.setByteArray("Data16", metadataArray);
+            }
         }
     }