Address fifth round of review comments

Author: anthony-etim

keras_hub/src/vllm/tokenizer.py

@@ -291,6 +291,11 @@ def decode(self, token_ids, skip_special_tokens=False, **kwargs):
                 for token_id in token_ids
                 if int(token_id) not in special_ids
             ]
+        # Empty input (or everything filtered as special) decodes to "".
+        # len(), not truthiness: token_ids may be a numpy array, whose
+        # truth value is ambiguous.
+        if len(token_ids) == 0:
+            return ""
         text = self.tokenizer.detokenize(token_ids)
         np_text = ops.convert_to_numpy(text)
         if hasattr(np_text, "item"):

keras_hub/src/vllm/tokenizer_test.py

@@ -81,6 +81,14 @@ def test_unknown_token_raises_in_convert_to_string(self):
         with self.assertRaises(KeyError):
             self.adapter.convert_tokens_to_string(["b", "not_a_token"])
 
+    def test_decode_empty_and_all_special(self):
+        self.assertEqual(self.adapter.decode([]), "")
+        # bos/eos only, all filtered out.
+        self.assertEqual(
+            self.adapter.decode([1, 2], skip_special_tokens=True), ""
+        )
+        self.assertEqual(self.adapter.decode(np.array([], dtype="int32")), "")
+
     def test_special_ids_drop_missing_token(self):
         # pad is absent, so only bos/eos ids appear (no defaulted id).
         self.assertEqual(self.adapter.all_special_ids, [1, 2])