Help message on invalid component

[Glutexo]

Passing an invalid component name prints a friendly help message instead of crashing with a stack trace. This is now consistent with a situation when an invalid switch is passed.

Fixes #179.

[Glutexo]

Shouldn’t I extend the with block to the Keyword.get call?

with {:ok, module} <-
  Map.fetch(@components, String.to_atom(component)),
  working_dir <- Keyword.get(switches, :working_dir, File.cwd!())

But Keyword.get never fails and thus doesn’t utilize the else block.

Another option would be to use Keyword.fetch instead, but it doesn’t support a default value. It would utilize the else block, but there, the default value would need to be assigned. I tried to write a code doing that and it was too complicated and didn’t make any sense. Keyword.fetch would only be useful if a missing keyword was a fatal error.

[nappex]

Nice 👍