Here is an example where someone had an old origin/master lying around that didn't share a common ancestor with main (their patch stack) and therefore when they checked out master it created a local branch called master based on origin/master which then resulted in the state computation of git ps failing because it could not find a common ancestor between master and origin/main (the base of the stack) when they would run gps ls.
See error output.
thread 'main' panicked at src/ps/public/list.rs:314:14:
called `Result::unwrap()` on an `Err` value: GetListLocalBranchesWithInfoFailed(GetListBranchInfoFailed(GetPatchInfoCollectionFailed(GetCommonAncestor(MergeBase { one:8d7ff522a0be7d0640cf32a3836c5fdab7420694, two: 4571c6a8f9a075c1f2768a95a9faaa252a3d9462, reason: Error { code: -3, klass: 22, message: "no merge base found" } }))))
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace