Incorrect error location when decoding certain fields with serde_yaml (serde_yaml bug)

[osa1]

This was originally reported in #425.

#[test]
fn notify_field_error() {
    let server_config = r#"
addr: irc.libera.chat
join: []
extra1: a
extra2: b
notify: [mentions]
"#;
    match serde_yaml::from_str::<Server>(server_config) {
        Ok(ok) => {
            dbg!(ok);
            panic!("Config parsing should've been failed");
        }
        Err(err) => {
            dbg!(err);
        }
    }
}

(add this to crates/libtiny_tui/src/config.rs)

Here the problem is notify field is a sequence, but it should be a string.

The error currently looks like this: (tiny efa1d22, uses serde 1.0.193 and serde_yaml 0.8.26)

[crates/libtiny_tui/src/config.rs:538] err = Message(
    "invalid type: sequence, expected string or map",
    Some(
        Pos {
            marker: Marker {
                index: 5,
                line: 2,
                col: 4,
            },
            path: ".",
        },
    ),
)

Here the line number is incorrect, it should've been 5 (or 4 if it's 0 based).

This is a serde_yaml bug, first reported in 2019: dtolnay/serde-yaml#128.

To work around the bug, we could manually "flatten" the TabConfig type in server, channel, and default configs, keep this bug open, and revert the change if the bug in serde_yaml is fixed one day.