Line number quoted in parsing errors is fairly useless

It looks like the line number which is shown in parsing errors is relative to the part of the file that is checked by the individual features, making it all but useless.

Either remove the line number, or fix it so it relates to the entire file.

Start by locating the parser and feature-specific validation paths that produce parsing errors, then reproduce the reported line number with a multi-line .asf.yaml file. Confirm whether the number is relative to a feature's input or the whole file. Done means either removing the line number or making it refer to the entire file, with a regression test for the chosen behavior.

Written by the indexing model from the issue text.