Not to detract from the good points made here, but it does confuse me to see "panic!()’s are hiding even in the most innocuous places like unwrap() and expect()

Not to detract from the good points made here, but it does confuse me to see "panic!()’s are hiding even in the most innocuous places like unwrap() and expect() calls". They're not innocuous at all -- they should stand out just as much as writing panic!(). Panicking is literally unwrap and expect's only job.