Fix 20w21a

For some reason, dimension data is handled through DataFixerUpper, using a Codec to generate the right NBT.

It specifically uses Encoder.encodeStart with NBTDynamicOps, and then errors if it returns a non-present DataResult, but that's a bit more noise than we care about.  We can just pretend that there's a regular encode function that knows to use NBT.

burger/toppings/packetinstructions.py

@@ -314,10 +314,19 @@ def operations(classloader, classname, classes, verbose, args=None,
                             )
                     elif num_arguments == 2:
                         if arg_type == "java/lang/String" and descriptor.args[1].name == "int":
-                            max_length = arguments[1] # not using this at the time
+                            max_length = arguments[1] # not using this at this time
                             operations.append(Operation(instruction.pos, "write",
                                                         type="string",
                                                         field=field))
+                        elif arg_type == "com/mojang/serialization/Codec":
+                            codec = arguments[0]
+                            value = arguments[1]
+                            # This isn't the exact syntax used by DataFixerUpper,
+                            # but it's close enough for our purposes
+                            field = "%s.encode(%s)" % (codec, value)
+                            operations.append(Operation(instruction.pos, "write",
+                                                        type="nbtcompound",
+                                                        field=field))
                         else:
                             raise Exception("Unexpected descriptor " + desc)
                     else: