Minor cleanup of file picker file gathering logic (#1683)

* Refactor file picker filetype filter logic to remove panic, make clearer

An unwrap was unneccesarily present due to a prior contribution of mine
which was before I had any understanding of error handling in Rust. I've
also swapped a match for an if let, as was originally suggested in the
original pull request adding filetype filtering, but was merged before I
could address.

* Add some comments to the file picker code for clarity

* Switch to expect instead of ignoring type def error

0 files changed, 0 insertions, 0 deletions