package can't be installed because `assertive` is defunct

## Summary

- Package `assertive` has been [removed from CRAN](https://cran.r-project.org/web/packages/assertive/index.html)
- Because of this, packages that depend on `assertive` can't be installed automatically (with, e.g., `devtools::install_github("BAAQMD/geotools"); nstallation will fail
- This package relies on `assertive.numbers` in a really unnecessary way

Start by checking the package dependency metadata and locating references to assertive.numbers. Confirm which dependency and code paths prevent installation, then verify that the package installs successfully without the defunct assertive dependency.

Written by the indexing model from the issue text.