refine code to prevent exception (#1231)

### What problem does this PR solve?


### Type of change

- [x] Refactoring

rag/app/naive.py

                     txt += l
         sections = []
         for sec in txt.split("\n"):
-            if num_tokens_from_string(sec) > 10 * parser_config.get("chunk_token_num", 128):
+            if num_tokens_from_string(sec) > 10 * int(parser_config.get("chunk_token_num", 128)):
                 sections.append((sec[:int(len(sec)/2)], ""))
                 sections.append((sec[int(len(sec)/2):], ""))
             else:
 
     elif re.search(r"\.json$", filename, re.IGNORECASE):
         callback(0.1, "Start to parse.")
-        sections = JsonParser(parser_config.get("chunk_token_num", 128))(binary)
+        sections = JsonParser(int(parser_config.get("chunk_token_num", 128)))(binary)
         sections = [(l, "") for l in sections if l]
         callback(0.8, "Finish parsing.")
 
 
     st = timer()
     chunks = naive_merge(
-        sections, parser_config.get(
-            "chunk_token_num", 128), parser_config.get(
+        sections, int(parser_config.get(
+            "chunk_token_num", 128)), parser_config.get(
             "delimiter", "\n!?。；！？"))
 
     res.extend(tokenize_chunks(chunks, doc, eng, pdf_parser))