On brand new repo, handle case where PR introduces pom.xml (or other package manager config file)

Is your feature request related to a problem? Please describe.
In a brand new repo, it is initialized with no package manager configuration. e.g.

$ git status
On branch develop
Your branch is up to date with 'origin/develop'.

nothing to commit, working tree clean
$ ls
README.md

Where the PR introduces the pom.xml, frogbot fails because no package manager is found in base branch:

10:36:19 [Debug] Downloading xxx-my-org/yyy-my-repo from branch:<develop>
10:36:19 [Debug] Downloading repository completed
10:36:19 [🔵Info] Auditing project:
10:36:19 [🚨Error] could not determine the package manager / build tool used by this project.

Describe the solution you'd like to see
Option to ignore missing package manager in base branch (and assume list of dependencies is empty), or generate warning instead of error.

Describe alternatives you've considered
First option is to not configure frogbot until pom is added to repo. However this poses the problem that the initial commit of pom.xml might introduce issues which are not found by frogbot, as they are not new issues in subsequent frogbot runs.

Additional context
Add any other context or screenshots about the feature request here.

Start by tracing package-manager detection for a new repository whose base branch has only README.md while a pull request introduces pom.xml. Compare the base-branch and pull-request states, then verify that missing package-manager configuration is treated as an empty dependency set or warning and that the introduced configuration is still audited.