Fix: Error in circuit visualization of decomposable gates

[vinayswamik]

Fixes #209

Summary of changes

• This fix makes axes handling more robust by first checking whether axis is a numpy array and, if so, converting it into a flat list of Axes objects.
• If axis is a single instance, it’s wrapped in a list to ensure consistency. Finally, if axis is already a list of Axes, it’s left unchanged.
• This guarantees that downstream code always works with a proper list of Axes objects, regardless of the number of subplots.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

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[TheGupta2012]

Thanks for fixing this @vinayswamik ! While testing out the code I see that the gates are unrolled by default -

from pyqasm import loads
from pyqasm.printer import mpl_draw

qasm = """
    OPENQASM 3.0;
    qubit[2] q1;
    qreg q[3];
    creg c[3];
    ccx q[0], q[1], q1[0];
    crx (0.1) q[0], q[1];
    rccx q[0], q[1], q1[0];
    cz q[0], q[1];
    """
circ = loads(qasm)
mpl_draw(circ, filename = 'test.png')

Can you see why this is happening? Ideally we should represent the gates as is, unless an unroll is called internally

[vinayswamik]

The reason is program.unroll() is calling in the beginning of mpl_draw function.

[TheGupta2012]

Hmm, ideally it should be validate as we don't wanna change the representation unless the user triggers an unroll command.

[vinayswamik]

Hmm, ideally it should be validate as we don't wanna change the representation unless the user triggers an unroll command.

That's true. actually we can open it as new issue.
lmk or else we can start refactor from here.

[TheGupta2012]

Let's move that into a separate issue as current changes look fine to me

[TheGupta2012]

Can you also add a CHANGELOG entry? I know we tend to forget that (including myself!) but trying to make that into a habit here. Should be good to merge post that.

[ryanhill1]

Regarding changelog reminders, we can also port over this workflow from qBraid-SDK: https://github.com/qBraid/qBraid/blob/main/.github/workflows/pr-compliance.yml