Missing trailing newline on error with disabled help flag and subcommand

[jonathanmorley]

Please complete the following tasks

• I have searched the discussions
• I have searched the existing issues

Rust Version

1.54.0

Clap Version

master

Minimal reproducible code

fn main() {
    let app = App::new("foo")
        .subcommand(App::new("sub"))
        .setting(AppSettings::DisableHelpFlag)
        .setting(AppSettings::DisableHelpSubcommand);
}

Steps to reproduce the bug with the above code

cargo run -- help

Actual Behaviour

The help message does not contain a trailing newline

Expected Behaviour

The help message should contain a trailing newline

Additional Context

https://github.com/clap-rs/clap/pull/2786/files#r715734272

Debug Output

No response

[epage]

The problem is in src/parser/error.rs. Instead of the code focusing only on leading or trailing newlines for each section, it mixes them. usage and try_help use leading newlines but try_help also uses a trailing newline, if its used.

As a short term solution, we could add an else clause in try_help that adds a trailing newline. Ideally, we'd better organize this so it was more predictable of what happens.