Update convert-hf-to-gguf.py

Replacing with a less risky alternative to the 'assert' statement

convert-hf-to-gguf.py

@@ -967,7 +967,9 @@ def set_vocab(self):
         from transformers import AutoTokenizer
         tokenizer = AutoTokenizer.from_pretrained(dir_model)
         vocab_size = hparams.get("vocab_size", len(tokenizer.vocab))
-        assert max(tokenizer.vocab.values()) < vocab_size
+        if max(tokenizer.get_vocab().values()) >= vocab_size:
+            raise ValueError("Vocabulary size exceeds expected maximum size.")
+
 
         reverse_vocab: dict[int, str] = {id_: encoded_tok for encoded_tok, id_ in tokenizer.vocab.items()}
         added_vocab = tokenizer.get_added_vocab()