Improve quality of error messages

[akbyrd]

The error messages from Hugo consist of multiple "frames" all run together as a single line. It's really hard to visually parse.

Example:

ERROR render of "D:/Dev/akbyrd.dev/content/tests/6-test-emoji.md" failed: "D:\Dev\akbyrd.dev\layouts\_default\baseof.html:30:9": execute of template failed: template: _default/single.html:30:9: executing "_default/single.html" at <partial "resource" (dict "Name" "favicon.ico" "Rename" false)>: error calling partial: "D:\Dev\akbyrd.dev\layouts\partials\resource.html:67:24": execute of template failed: template: partials/resource.html:67:24: executing "partials/resource.html" at <$resource.Width>: error calling Width: this method is only available for image resources

In a terminal

In a browser

Honestly, I can't make heads or tails of this. Even trying to figure out where the line breaks should be is confusing. Maybe something like this?

ERROR
render of "D:/Dev/akbyrd.dev/content/tests/6-test-emoji.md" failed:
	"D:\Dev\akbyrd.dev\layouts\_default\baseof.html:30:9":
execute of template failed: template: _default/single.html:30:9:
	executing "_default/single.html" at <partial "resource" (dict "Name" "favicon.ico" "Rename" false)>:
	error calling partial: "D:\Dev\akbyrd.dev\layouts\partials\resource.html:67:24":
execute of template failed: template: partials/resource.html:67:24:
	executing "partials/resource.html" at <$resource.Width>:
	error calling Width: this method is only available for image resources

I think this is closer to ideal

ERROR Method "Width" is only available for image resources
	layouts/partials/resource.html:67:24:  at {{ $width = $resource.Width }}
	layouts/_default/baseof.html:30:9:     at {{ with partial "resource" (dict "Name" "favicon.ico" "Rename" false) -}}
	layouts/_default/single.html           
	content/tests/6-test-emoji.md:         

As it stands today

• There's no visual line to follow for either locations or error messages
• The same locations are listed multiple times.
• Paths are sometimes relative and sometimes absolute
• There are locations mentioned that don't even exist (single.html is 23 lines long)
• Column numbers don't quite match reality (issues with whitespace maybe?)
• Back and forward slashes are mixed, which makes searching with Ctrl+F harder.
• Impractical to parse with an automated tool (e.g. a vscode problem matcher)

I don't know how much control Hugo has and how much this is dictated by Go templates, but I figure it's worth poking at.