Return continuation even if no chat data

pytchat/tool/download/asyncdl.py

@@ -1,4 +1,3 @@
-
 import aiohttp
 import asyncio
 import json
@@ -105,7 +104,7 @@ def download_patch(callback, blocks, video_id):
             if callback:
                 callback(actions, last - first)
             return Patch(actions, continuation, first, last)
-        return Patch()
+        return Patch(continuation = continuation)
     """
     allocate workers and assign blocks.
     """   

pytchat/tool/download/patch.py

@@ -22,7 +22,6 @@ def fill(block:Block, patch:Patch):
         if line_offset < block_end:
             break
         patch.chats.pop()
-        
     set_patch(block, patch._replace(
         continuation = None,
         last = line_offset
@@ -34,15 +33,16 @@ def fill(block:Block, patch:Patch):
 
 def split(parent_block:Block, child_block:Block, patch:Patch):
     parent_block.during_split = False
-    """patch overlaps with parent_block"""
     if patch.first <= parent_block.last:
+        ''' When patch overlaps with parent_block,
+        discard this block. '''
         child_block.continuation = None
         ''' Leave child_block.during_split == True 
-         to exclude from during_split sequence.'''
+         to exclude from during_split sequence. '''
         return    
     child_block.during_split = False
-    child_block.first=patch.first
-    parent_block.end =patch.first
+    child_block.first = patch.first
+    parent_block.end = patch.first
     fill(child_block, patch)