Removed last variable selection and added test case for no name available

Author: Raj-Parekh24

pytensor/graph/basic.py

@@ -611,9 +611,7 @@ def convert_string_keys_to_variables():
                                 f"Found {length_of_nodes_with_matching_names} pytensor variables with name {i}"
                             )
                         process_input_to_values[
-                            nodes_with_matching_names[
-                                length_of_nodes_with_matching_names - 1
-                            ]
+                            nodes_with_matching_names[0]
                         ] = inputs_to_values[i]
                 else:
                     process_input_to_values[i] = inputs_to_values[i]

tests/graph/test_basic.py

@@ -313,6 +313,13 @@ def test_eval_errors_having_mulitple_variables_same_name(self):
         with pytest.raises(Exception, match="Found 2 pytensor variables with name e"):
             t.eval({"e": 1})
 
+    def test_eval_errors_with_no_name_exists(self):
+        e = scalars("e")
+        t = e + 1
+        t.name = "p"
+        with pytest.raises(Exception, match="o not found in graph"):
+            t.eval({"o": 1})
+
 
 class TestAutoName:
     def test_auto_name(self):