# Buggy code
def __init__(self, kak_basis_gate=None, force_consolidate=False, basis_gates=None):
    """ConsolidateBlocks initializer.

    Args:
        kak_basis_gate (Gate): Basis gate for KAK decomposition.
        force_consolidate (bool): Force block consolidation
        basis_gates (List(str)): Basis gates from which to choose a KAK gate.
    """
    super().__init__()
    self.basis_gates = basis_gates
    self.force_consolidate = force_consolidate

    if kak_basis_gate is not None:
        self.decomposer = TwoQubitBasisDecomposer(kak_basis_gate)
    elif basis_gates is not None:
        kak_basis_gate = unitary_synthesis._choose_kak_gate(basis_gates)
        self.decomposer = TwoQubitBasisDecomposer(kak_basis_gate)
    else:
        self.decomposer = TwoQubitBasisDecomposer(CXGate())


# Traceback (qiskit.exceptions.QiskitError)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/jul/Work/Qiskit/qiskit-terra/qiskit/compiler/transpile.py", line 214, in transpile
circuits = parallel_map(_transpile_circuit, list(zip(circuits, transpile_args)))
File "/Users/jul/Work/Qiskit/qiskit-terra/qiskit/tools/parallel.py", line 108, in parallel_map
return [task(values[0], *task_args, **task_kwargs)]
File "/Users/jul/Work/Qiskit/qiskit-terra/qiskit/compiler/transpile.py", line 304, in _transpile_circuit
pass_manager = level_3_pass_manager(pass_manager_config)
File "/Users/jul/Work/Qiskit/qiskit-terra/qiskit/transpiler/preset_passmanagers/level3.py", line 176, in level_3_pass_manager
ConsolidateBlocks(basis_gates=basis_gates),
File "/Users/jul/Work/Qiskit/qiskit-terra/qiskit/transpiler/basepasses.py", line 31, in __call__
pass_instance = type.__call__(cls, *args, **kwargs)
File "/Users/jul/Work/Qiskit/qiskit-terra/qiskit/transpiler/passes/optimization/consolidate_blocks.py", line 63, in __init__
self.decomposer = TwoQubitBasisDecomposer(kak_basis_gate)
File "/Users/jul/Work/Qiskit/qiskit-terra/qiskit/quantum_info/synthesis/two_qubit_decompose.py", line 293, in __init__
basis = self.basis = TwoQubitWeylDecomposition(Operator(gate).data)
File "/Users/jul/Work/Qiskit/qiskit-terra/qiskit/quantum_info/operators/operator.py", line 103, in __init__
raise QiskitError("Invalid input data format for Operator")
qiskit.exceptions.QiskitError: 'Invalid input data format for Operator'

# Fixed code
def __init__(self, kak_basis_gate=None, force_consolidate=False, basis_gates=None):
    """ConsolidateBlocks initializer.

    Args:
        kak_basis_gate (Gate): Basis gate for KAK decomposition.
        force_consolidate (bool): Force block consolidation
        basis_gates (List(str)): Basis gates from which to choose a KAK gate.
    """
    super().__init__()
    self.basis_gates = basis_gates
    self.force_consolidate = force_consolidate

    if kak_basis_gate is not None:
        self.decomposer = TwoQubitBasisDecomposer(kak_basis_gate)
    elif basis_gates is not None:
        kak_basis_gate = unitary_synthesis._choose_kak_gate(basis_gates)
        if kak_basis_gate is not None:
            self.decomposer = TwoQubitBasisDecomposer(kak_basis_gate)
        else:
            self.decomposer = None
    else:
        self.decomposer = TwoQubitBasisDecomposer(CXGate())