> Do you think it makes sense to have both getConvergence and getMagnification?

I would keep both I think.  It makes sense to provide access to the raw values (gamma, kappa) as well as convenient derived quantities.

The other one that I might add is getReducedShear, which is probably the one we actually want to use when we apply to galaxies, right?  i.e. That's the one that config should use when the `shear` type is PowerSpectrumShear or NFWHaloShear.  And also the one that should be used with a combined `applyLensing` function if we add that feature.