Make more informative error messages

```
bundle exec jekyll serve --trace --drafts
Configuration file: /Web/_config.yml
LaTeX: 3 macros loaded (1 updated)
Source: /Web
Destination: /Web/_site
Incremental build: disabled. Enable with --incremental
Generating...
bundler: failed to load command: jekyll (/Web/vendor/bundle/ruby/3.3.0+0/bin/jekyll)
/Web/vendor/bundle/ruby/3.3.0+0/gems/htmlbeautifier-1.4.2/lib/htmlbeautifier/parser.rb:37:in `rescue in dispatch': Unmatched sequence on line 7 (RuntimeError)
from /Web/vendor/bundle/ruby/3.3.0+0/gems/htmlbeautifier-1.4.2/lib/htmlbeautifier/parser.rb:31:in `dispatch'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/htmlbeautifier-1.4.2/lib/htmlbeautifier/parser.rb:18:in `scan'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/htmlbeautifier-1.4.2/lib/htmlbeautifier.rb:28:in `block in beautify'
from :90:in `tap'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/htmlbeautifier-1.4.2/lib/htmlbeautifier.rb:27:in `beautify'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-tidy-0.2.2/lib/jekyll/tidy.rb:31:in `output_clean'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-tidy-0.2.2/lib/jekyll/tidy.rb:58:in `block in '
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/hooks.rb:103:in `block in trigger'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/hooks.rb:102:in `each'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/hooks.rb:102:in `trigger'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/page.rb:179:in `trigger_hooks'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:573:in `render_regenerated'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:564:in `block in render_pages'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:563:in `each'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:563:in `render_pages'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:211:in `render'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:80:in `process'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/command.rb:28:in `process_site'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/commands/build.rb:65:in `build'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/commands/build.rb:36:in `process'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/command.rb:91:in `block in process_with_graceful_fail'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/command.rb:91:in `each'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/command.rb:91:in `process_with_graceful_fail'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/commands/serve.rb:86:in `block (2 levels) in init_with_program'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `block in execute'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `each'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `execute'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/mercenary-0.4.0/lib/mercenary/program.rb:44:in `go'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/mercenary-0.4.0/lib/mercenary.rb:21:in `program'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/exe/jekyll:15:in `'
from /Web/vendor/bundle/ruby/3.3.0+0/bin/jekyll:25:in `load'
from /Web/vendor/bundle/ruby/3.3.0+0/bin/jekyll:25:in `'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli/exec.rb:58:in `load'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli/exec.rb:58:in `kernel_load'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli/exec.rb:23:in `run'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli.rb:491:in `exec'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/vendor/thor/lib/thor.rb:392:in `dispatch'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli.rb:34:in `dispatch'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/vendor/thor/lib/thor/base.rb:485:in `start'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli.rb:28:in `start'
from /.rubies/ruby-yjit/lib/ruby/gems/3.3.0+0/gems/bundler-2.5.0.dev/libexec/bundle:45:in `block in '
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/friendly_errors.rb:117:in `with_friendly_errors'
from /.rubies/ruby-yjit/lib/ruby/gems/3.3.0+0/gems/bundler-2.5.0.dev/libexec/bundle:33:in `'
from /.local/share/gem/ruby/3.0.0/bin/bundle:25:in `load'
from /.local/share/gem/ruby/3.0.0/bin/bundle:25:in `'
/Web/vendor/bundle/ruby/3.3.0+0/gems/htmlbeautifier-1.4.2/lib/htmlbeautifier/parser.rb:33:in `dispatch': Unmatched sequence (RuntimeError)
from /Web/vendor/bundle/ruby/3.3.0+0/gems/htmlbeautifier-1.4.2/lib/htmlbeautifier/parser.rb:18:in `scan'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/htmlbeautifier-1.4.2/lib/htmlbeautifier.rb:28:in `block in beautify'
from :90:in `tap'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/htmlbeautifier-1.4.2/lib/htmlbeautifier.rb:27:in `beautify'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-tidy-0.2.2/lib/jekyll/tidy.rb:31:in `output_clean'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-tidy-0.2.2/lib/jekyll/tidy.rb:58:in `block in '
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/hooks.rb:103:in `block in trigger'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/hooks.rb:102:in `each'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/hooks.rb:102:in `trigger'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/page.rb:179:in `trigger_hooks'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:573:in `render_regenerated'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:564:in `block in render_pages'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:563:in `each'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:563:in `render_pages'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:211:in `render'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/site.rb:80:in `process'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/command.rb:28:in `process_site'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/commands/build.rb:65:in `build'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/commands/build.rb:36:in `process'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/command.rb:91:in `block in process_with_graceful_fail'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/command.rb:91:in `each'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/command.rb:91:in `process_with_graceful_fail'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/lib/jekyll/commands/serve.rb:86:in `block (2 levels) in init_with_program'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `block in execute'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `each'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `execute'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/mercenary-0.4.0/lib/mercenary/program.rb:44:in `go'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/mercenary-0.4.0/lib/mercenary.rb:21:in `program'
from /Web/vendor/bundle/ruby/3.3.0+0/gems/jekyll-4.3.2/exe/jekyll:15:in `'
from /Web/vendor/bundle/ruby/3.3.0+0/bin/jekyll:25:in `load'
from /Web/vendor/bundle/ruby/3.3.0+0/bin/jekyll:25:in `'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli/exec.rb:58:in `load'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli/exec.rb:58:in `kernel_load'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli/exec.rb:23:in `run'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli.rb:491:in `exec'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/vendor/thor/lib/thor.rb:392:in `dispatch'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli.rb:34:in `dispatch'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/vendor/thor/lib/thor/base.rb:485:in `start'
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/cli.rb:28:in `start'
from /.rubies/ruby-yjit/lib/ruby/gems/3.3.0+0/gems/bundler-2.5.0.dev/libexec/bundle:45:in `block in '
from /.rubies/ruby-yjit/lib/ruby/3.3.0+0/bundler/friendly_errors.rb:117:in `with_friendly_errors'
from /.rubies/ruby-yjit/lib/ruby/gems/3.3.0+0/gems/bundler-2.5.0.dev/libexec/bundle:33:in `'
from /.local/share/gem/ruby/3.0.0/bin/bundle:25:in `load'
from /.local/share/gem/ruby/3.0.0/bin/bundle:25:in `'
make: *** [makefile:6: run] Error 1
```
I do not know what is wrong and how do I fix it. Please make error messages more informative. For example:

> In project/file.html is bad sequence on line 43
>

Reproduce the failure with `bundle exec jekyll serve --trace --drafts`, then start at `jekyll-tidy/lib/jekyll/tidy.rb:31` and the `htmlbeautifier/parser.rb` dispatch shown in the trace. Done means malformed HTML errors identify the project file, the relevant line, and the problematic sequence instead of only reporting `Unmatched sequence`.

Written by the indexing model from the issue text.