Raise proper error when inputs are missing (#22)

pargraph/about.py

@@ -1 +1 @@
-__version__ = "0.9.0"
+__version__ = "0.9.1"

pargraph/graph/objects.py

@@ -843,9 +843,13 @@ def _convert_graph_to_dict(
             for input_key in self.inputs.keys():
                 graph_key = f"input_{input_key.key}_{uuid.uuid4().hex}"
                 # if input key is not in inputs, use the default value
-                dict_graph[graph_key] = (
-                    inputs[input_key.key] if input_key.key in inputs else self.consts[self.inputs[input_key]].to_value()
-                )
+                if input_key.key in inputs:
+                    dict_graph[graph_key] = inputs[input_key.key]
+                elif self.inputs[input_key] is not None:
+                    dict_graph[graph_key] = self.consts[self.inputs[input_key]].to_value()
+                else:
+                    raise ValueError(f"input '{input_key.key}' not found in provided inputs")
+
                 key_to_uuid[input_key] = graph_key
 
         # assign random keys to all node paths and node output paths beforehand

tests/test_graph_generation.py

@@ -317,3 +317,11 @@ def add(x: int, y: int = 1) -> int:
             return x + y
 
         self.assertEqual(self.engine.get(*add.to_graph().to_dict(x=2))[0], add(x=2))
+
+    def test_missing_input(self):
+        @graph
+        def add(x: int, y: int) -> int:
+            return x + y
+
+        with self.assertRaises(ValueError):
+            add.to_graph().to_dict(x=2)