Returning `None` is not supported kernel functions

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Describe the bug

Does not work

import cudaq
import numpy as np

@cudaq.kernel
def test_k() -> complex:
    return None

print(test_k()) # cudaq.kernel.ast_bridge.CompilerError: program.py:14: error: unhandled constant value (offending source -> None)

#Works

def test() -> complex:
    return None

print(test())

Steps to reproduce the bug

import cudaq
import numpy as np

@cudaq.kernel
def test_k() -> complex:
    return None

print(test_k())

Expected behavior

None is printed

Is this a regression? If it is, put the last known working version (or commit) here.

Not a regression

Environment

• CUDA Quantum version:
• Python version:
• C++ compiler:
• Operating system:

Suggestions

No response

Start by running the Python reproducer with the CUDA Quantum kernel decorator and inspect the compiler path that reports the unhandled constant value for None. Compare the decorated kernel with the ordinary Python function, then add coverage for returning None and verify that the expected behavior is produced.