Properly calculate the size of INewChunk#getIntBiomeArray

This array is written to the PacketBuffer using
PacketBuffer#writeVarIntArray, which writes both the array size and
individual array elements as VarInts. However, JEID's calculation of the
array size was leaving out the array length prefix, and assuming that
each array element was exactly four bytes. Since a VarInt-encoded
integer can range from 1 to 5 bytes, the calculation of the array size
could end up being smaller than the actual number of bytes written,
causing a crash.

This commit makes JEID properly calculate the size of getIntBiomeArray,
ensuring that the allocated buffer size always matches the number of
bytes written.

src/main/java/org/dimdev/jeid/mixin/core/MixinSPacketChunkData.java

@@ -29,9 +29,25 @@ public boolean getIsFullChunk(SPacketChunkData packet) {
         return false;
     }
 
-    @Redirect(method = "calculateChunkSize", at = @At(value = "INVOKE", target = "Lnet/minecraft/world/chunk/Chunk;getBiomeArray()[B"))
-    private byte[] getBiomeArray(Chunk chunk) {
-        INewChunk newChunk = (INewChunk) chunk;
-        return new byte[newChunk.getIntBiomeArray().length * 4];
+    @Inject(method = "calculateChunkSize", at = @At(value = "RETURN"), cancellable = true)
+    public void onReturn(Chunk chunkIn, boolean p_189556_2_, int p_189556_3_, CallbackInfoReturnable<Integer> ci) {
+        if (this.isFullChunk()) {
+            int size = ci.getReturnValue();
+
+            // First, we subtract off the length added by Vanilla (the line 'i += chunkIn.getBiomeArray().length;')
+            size -= chunkIn.getBiomeArray().length;
+
+            // Now, we add on the actual length of the VarIntArray we're going to be writing in extractChunkData
+            size += this.getVarIntArraySize(((INewChunk) chunkIn).getIntBiomeArray());
+            ci.setReturnValue(size);
+        }
+    }
+
+    private int getVarIntArraySize(int[] array) {
+        int size = PacketBuffer.getVarIntSize(array.length);
+        for (int i: array) {
+            size += PacketBuffer.getVarIntSize(i);
+        }
+        return size;
     }
 }