Loading a pre-trained model with custom wavelength_grid requires sufficient bandwidth to see all the lines

[gully]

SparseLinearEmulator (and all the emulators for that matter) support a neat feature-- you can hand-in a wavelength_grid vector that is different from the native precomputed synthetic spectral model's wavelength coodinates. That strategy allows us to pass in logarithmically spaced points which facilitates later Doppler convolution steps. Yay!

A problem arises if you pass in too small of a bandwidth because a given line may then exist outside of the wavelength grid.

Two solutions:

1. Check for and then demand that the bandwidth be at least as wide as the reddest and bluest wavelengths.
2. Truncate the input lines to only include those in the handed-in bandwidth.

The right answer is problem-specific and to be determinded.