Empty or all-blank string should not be an error?

[sourcefrog]

Today you get

> cargo r --example dump /dev/null
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/examples/dump /dev/null`

thread 'main' (394033) panicked at examples/dump.rs:18:51:
called `Result::unwrap()` on an `Err` value: ParseError { line: 1, offset: 0, fragment: "", kind: TakeUntil }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

It seems from

gitpatch/src/ast.rs

Lines 83 to 84 in 5a3b88d

	/// Attempt to parse as many patches as possible from the given string. This is useful for when
	/// you have a complete diff of many files. String must contain at least one patch.

this is intentional but IMO it's not the best UI.