[BUG] Torch interface incompatibility with finite-shot mid-circuit measurements

[trbromley]

Expected behavior

Able to execute the following QNode which includes:

• Use of torch interface
• Use of mid-circuit measurements
• Finite shots and a sample-based output

Actual behavior

Error when following QNode is executed.

Additional information

No response

Source code

import pennylane as qml
import torch

dev = qml.device("default.qubit", shots=10)

@qml.qnode(dev, interface="torch")
def f(x):
    qml.RX(x, 0)
    for i in range(5):
        qml.Hadamard(0)
        qml.measure(0)
    return qml.sample(qml.PauliX(0))

x = torch.tensor(0.4)
f(x)

Tracebacks

AttributeError: 'Tensor' object has no attribute 'append'

System information

On the PL dev branch.

Existing GitHub issues

• [X] I have searched existing GitHub issues to make sure the issue does not already exist.

[trbromley]

Related to this forum post.

[trbromley]

CC @vincentmr.

[albi3ro]

Different errors, but also fails for jax and tensorflow.