[BUG] KeyError in init_subroutine_scope when custom_gates key missing in Context initialization #8931
Description
Expected behavior
The Context class should handle missing optional keys. Specifically, if custom_gates is not provided during initialization, it should default to an empty dictionary or similar structure to avoid runtime errors.
Actual behavior
When a Context object is initialized with a dictionary that does not contain the custom_gates key, calling init_subroutine_scope results in a KeyError.
Additional information
No response
Source code
from pennylane.io.qasm_interpreter import Context
class MockName:
def __init__(self, name):
self.name = name
class MockSubroutineDefinition:
def __init__(self, name, arguments, body):
self.name = name
self.arguments = arguments
self.body = body
context_dict = {'scopes': {'subroutines': {}}}
ctx = Context(context_dict)
node = MockSubroutineDefinition(name=MockName('subroutine_example'), arguments=[], body=[])
ctx.init_subroutine_scope(node)Tracebacks
Traceback (most recent call last):
File "/path/to/dict_error.py", line 16, in <module>
ctx.init_subroutine_scope(node)
File "/path/to/pennylane/io/qasm_interpreter.py", line 335, in init_subroutine_scope
"custom_gates": self.scopes["custom_gates"],
~~~~~~~~~~~^^^^^^^^^^^^^^^^
KeyError: 'custom_gates'System information
Name: pennylane
Version: 0.44.0
Summary: PennyLane is a cross-platform Python library for quantum computing, quantum machine learning, and quantum chemistry. Train a quantum computer the same way as a neural network.
Home-page:
Author:
License:
Location: /home/xyzb/miniconda3/envs/qml440/lib/python3.11/site-packages
Platform info: Linux-6.6.87.2-microsoft-standard-WSL2-x86_64-with-glibc2.39
Python version: 3.11.14
Numpy version: 2.4.1
Scipy version: 1.17.0
JAX version: None
Installed devices:
- default.clifford (pennylane-0.44.0)
- default.gaussian (pennylane-0.44.0)
- default.mixed (pennylane-0.44.0)
- default.qubit (pennylane-0.44.0)
- default.qutrit (pennylane-0.44.0)
- default.qutrit.mixed (pennylane-0.44.0)
- default.tensor (pennylane-0.44.0)
- null.qubit (pennylane-0.44.0)
- reference.qubit (pennylane-0.44.0)
- lightning.qubit (pennylane_lightning-0.44.0)Existing GitHub issues
- I have searched existing GitHub issues to make sure the issue does not already exist.