hurlfmt: Illegal headers from curl input cause panic

[theoforger]

What is the current bug behavior?

When using hurlfmt with the option --in curl, if the input file contains any illegal headers, the program would simply panic.

hurlfmt, when executed with --in curl, does not check the validity of headers before converting curl commands into the hurl file format. Illegal headers can make their way into the hurl file, and then cause issues with the parser hurl_core::parser::parse_hurl_file.

It's also worth mentioning that, with curl, illegal headers don't seem to result in a crash, nor does curl display any error messages. It simply ignores the header.

Steps to reproduce

1. Prepare a file with a curl command which contains an illegal header. For example:

# example.curl:
curl --header 'illegal-header' 'https://httpbin.org/status/200'

2. Use this file as an input for hurlfmt:

$ hurlfmt --in curl example.curl

3. Panic:

thread 'main' panicked at packages/hurl_core/src/error/mod.rs:228:38:
called `Option::unwrap()` on a `None` value
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Possible fixes

1. Add a safeguard in hurlfmt to check curl headers before conversion.
2. Handle this error in the parser. Display a proper error message if the header is illegal.