I have created two minimal working examples as public repos in Jason M. Osborne Bitbucket
The first repo BasicWebsite-Rmarkdown shows my file structure and organizational thought process and successfully uses without error an R-script with render_site. I wrote a recent blog post on this topic as a README. This minimal working example showed to me proof-of-concept that I could hopefully write a blog with my existing skills in RMarkdown and YAML. I then extended these new skills to render_book and my blog.
The second repo BasicWebsite-WithPosts-Rmarkdown shows a minimal working example of my thought process in the final creation of my Jason M. Osborne Blog.
The single post writing and rendering with Bookdown worked in bookdown_0.26 but broke in bookdown_0.27 due to
Error in stop_if_not_exists(input) :
Some files were not found: ./source-posts
I hope this second minimal working example helps y'all identify the error and a possible solution. As stated in the commit message of BasicWebsite-WithPosts-Rmarkdown , the file structure is source-body which renders via a R-script using render_site to a self-contained output folder while source-post renders via render_book (singlePost renderscript) to a self-contained folder output/posts. Again, this solution worked in 0.26 but not 0.27 because of the above message.
All of the, hopefully, full functioning repos were created on my laptop whose sessionInfo() is
R version 4.1.3 (2022-03-10)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Mojave 10.14.6
other attached packages:
loaded via a namespace (and not attached):
 digest_0.6.29 R6_2.5.1 jsonlite_1.8.0 magrittr_2.0.3 evaluate_0.15 highr_0.9
 stringi_1.7.6 rlang_1.0.2 jquerylib_0.1.4 bslib_0.3.1 rmarkdown_2.13 tools_4.1.3
 stringr_1.4.0 xfun_0.30 yaml_2.3.5 fastmap_1.1.0 compiler_4.1.3 htmltools_0.5.2
 knitr_1.38 sass_0.4.1
I hope that the information I have provided is what you need. This is my first time communicating about something this technical before. I am still pretty new to R, Rmarkdown, and Git so please let me know if there is anything else you need to help debug this error.
Jason M. Osborne
mathematician + educator + creative tinkerer + writer