chore: assert correct typing when using Probabilistic methods with Sparse reconcilers

[elephaint]

What happened + What you expected to happen

Probalistic methods are generally typed with Numpy arrays, however they also work with Sparse methods. These methods however generate scipy sparse matrices, and we should correctly set the dtype entering the methods to support both np.ndarray and scipy sparse matrices to clarify the code.

Versions / Dependencies

1.2

Reproduction script

n/a

Issue Severity

Low: It annoys or frustrates me.