ln_helper() may flip the exponent and compute \(\ln(1 / argument)\) for values below 1, reentering ln(...).  
If theres a scenario where the flipped exponent does not converge or leads back to a similar condition, infinite recursion (or very deep recursion) could occur.  
On certain edge casesextremely large or extremely small exponentthere might be repeated calls into ln(), eventually running out of gas or reverting. 
Add safeguards (e.g., if exponent is beyond some threshold, revert or approximate the limit) and thoroughly test lowmagnitude inputs (like \(x \approx 1e-6000\)) to verify that recursion terminates.
