Improve preset error messages

keras_nlp/utils/preset_utils.py

@@ -30,6 +30,10 @@
 
 def get_file(preset, path):
     """Download a preset file in necessary and return the local path."""
+    if not isinstance(preset, str):
+        raise ValueError(
+            f"A preset identifier must be a string. Received: preset={preset}"
+        )
     if preset.startswith(KAGGLE_PREFIX):
         if kagglehub is None:
             raise ImportError(
@@ -64,9 +68,19 @@ def get_file(preset, path):
             url,
             cache_subdir=os.path.join("models", subdir),
         )
-    else:
+    elif os.path.exists(preset):
         # Assume a local filepath.
         return os.path.join(preset, path)
+    else:
+        raise ValueError(
+            "Unknown preset identifier. A preset must be a one of:\n"
+            "1) a built in preset identifier like `'bert_base_en'`\n"
+            "2) a Kaggle Models handle like `'kaggle://keras/bert/bert_base_en'`\n"
+            "3) a path to a local preset directory like `'./bert_base_en`\n"
+            "Use `print(cls.presets.keys())` to view all built-in presets for "
+            "API symbol `cls`.\n"
+            f"Received: preset='{preset}'"
+        )
 
 
 def get_tokenizer(layer):

keras_nlp/utils/preset_utils_test.py

@@ -87,3 +87,10 @@ def test_preset_saving(self, cls, preset_name, tokenizer_type):
         self.assertAllEqual(
             model(model_input_data), restored_model(restored_model_input_data)
         )
+
+    def test_preset_errors(self):
+        with self.assertRaisesRegex(ValueError, "must be a string"):
+            AlbertClassifier.from_preset(AlbertClassifier)
+
+        with self.assertRaisesRegex(ValueError, "Unknown preset identifier"):
+            AlbertClassifier.from_preset("snaggle://bort/bort/bort")