Deployment to shinyapps failing due to CRAN dependency

I have a Shiny app that I am attempting to deploy to, but is failing. The repository with the app is here: GitHub - wjakethompson/ab-test

When I run rsconnect::deployApp(), I get the following error:

Error: Unhandled Exception: Child Task 1303183864 failed: 
Error building image: Error fetching MASS (7.3-58.4) source. 
<CRANPackageSource repo=''> unable to satisfy package: MASS (7.3-58.4)

I'm not specifying a specific version of MASS in the DESCRIPTION file, but it appears that the CRAN version of MASS is 7.3-60: CRAN - Package MASS

Any recommendations on how to get the app to deploy successfully?

I had this same issue and had to downgrade MASS to fix it. See similar post:

I had this problem on a Desktop but not on my laptop. I guess it depends on the R version or configuration. If what @swalkerCDD says does notwork, maybe try uninstalling R and installing it again... It May work!