unclear error message when calling cudaq.adjoint outside of a kernel

[mmvandieren]

Required prerequisites

• Consult the security policy. If reporting a security vulnerability, do not report the bug using this form. Use the process described in the policy to report the issue.
• Make sure you've read the documentation. Your issue may be addressed there.
• Search the issue tracker to verify that this hasn't already been reported. +1 or comment there if it has.
• If possible, make a PR with a failing test to give us a starting point to work on!

Describe the bug

There is no (or difficult to find) documentation on the cudaq.adjoint operator applied to a kernel to indicate that the behaviors below might not be allowed (unless one has a solid understanding of decorators, which I don't think all of our user base will necessarily have). The error message produced doesn't really help since it seems to indicate that this function doesn't even exist.

error message: module 'cudaq' has no attribute 'adjoint'

Steps to reproduce the bug

def quantum_fourier_transform(qubits: cudaq.qview):
    qubit_count = len(qubits)
    # Apply Hadamard gates and controlled rotation gates.
    for i in range(qubit_count):
        h(qubits[i])
        for j in range(i + 1, qubit_count):
            angle = (2 * np.pi) / (2**(j - i + 1))
            cr1(angle, [qubits[j]], qubits[i])

@cudaq.kernel
def test(q:int):
    qubits = cudaq.qvector(q)
    quantum_fourier_transform(qubits)

test_adj = cudaq.adjoint(test,3)

print(cudaq.draw(test_adj))

Expected behavior

An error message that better explains the problem and doesn't mislead the user that this operation isn't defined at all.

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

Not a regression

Environment

• CUDA Quantum version: 0.7.1
• Python version:
• C++ compiler:
• Operating system:

Suggestions

No response