Diophantine Equations of the form $x^2 - n y^2 = 1$

Question

I'm running into a problem with the execution of the Chakravala method of solving these equations. Running the algorithm through Python works up until $n=181$, at which point it executes all the way up until

$a=8524204405960630, b=633599123636484, k=-6$

I imagine after this point it runs into trouble due to $b$ being divisible by $6$. My question is, how can I avoid this? The resources I've seen don't explain what to do in that situation. Any and all assistance much appreciated.

Code snippet:

    for m in natural_number_generator(1):
    if (a + b * m) % abs(k) == 0:
        m_list.append(m)
        if m >= 2 * n:
            break

SOLVED: Simple solution, my program was running off of Float variables and running into issues once it reached the value of $2^52$ (which breaks the float), and switching from / to // by the divisions (so that it's using integer variables), solved it entirely. Thank you very much to Sil :)