`PauliwordOp` initialization error with trivial input in `cleanup()`

[HaoTy]

symmer/symmer/operators/base.py

Line 621 in 72ee3e9

return PauliwordOp([], [np.sum(self.coeff_vec)])

This PauliwordOp instantiation triggers the following assertion in the constructor, which I think is an unintended behavior. My guess is that the intended implementation is to use PauliwordOp.from_list() but was lost due to a previous refactor of the constructor.

symmer/symmer/operators/base.py

Line 63 in 72ee3e9

assert(symp_matrix.dtype == bool), 'Symplectic matrix must be defined over bools'