Assigning themes during package load

[teunbrand]

Hi there,

We've been preparing a new major release for ggplot2 and found an issue during a reverse dependency check.
The issue is that themes were assigned at build time, which may become version incompatible or emit warnings during package build (which is how we spotted this issue). We advise against this in the following text:
https://ggplot2.tidyverse.org/articles/ggplot2-in-packages.html#creating-a-new-theme
This PR assigns themes on load instead of during build.

You can test your code with the development version of ggplot2 by installing it as follows:

# install.packages("pak")
pak::pak("tidyverse/ggplot2")

We aim to release the new ggplot2 version in about 2 weeks, and hope you can submit a fix to CRAN around that time or let us know when ggplot2 should change. Hopefully this will inform you in a timely manner.

Best wishes,
Teun

[teunbrand]

This is just a simple reminder.