[ruby-core:110547] [Ruby master Bug#19093] gem uninstall, when prompting for gem selection it does not handle CTRL+D

["megatux (Cristian Molina)" <noreply@ruby-lang.org>]

Issue #19093 has been reported by megatux (Cristian Molina).

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Bug #19093: gem uninstall, when prompting for gem selection it does not handle CTRL+D
https://bugs.ruby-lang.org/issues/19093

* Author: megatux (Cristian Molina)
* Status: Open
* Priority: Normal
* ruby -v:  3.1.2p20
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
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Scenario: calling `gem uninstall some_gem` and there is more than 1 version of that gem installed
A list of the n versions of the gem is displayed and a prompt is waiting for a number of the item to uninstall.
When using ctrl+d on the prompt (I'm used to use ctrl+c/ctrl+d to interrupt CLI commands) an exception is raised :

```
gem uninstall activesupport 

Select gem to uninstall:
 1. activesupport-6.0.6
 2. activesupport-7.0.4
 3. All versions
> ERROR:  While executing gem ... (NoMethodError)
    undefined method `>=' for nil:NilClass

      elsif index >= 0 && index < list.size
                  ^^
```

Ctrl+c is handled correctly but for ctrl+d looks like `nil` is returned from #choose_from_list in rubygems/user_interaction.rb and then in Gem::Uninstaller class #uninstall in rubygems/uninstaller.rb that nil is not handled at all:

```ruby
      _, index = choose_from_list "Select gem to uninstall:", gem_names

      if index == list.size
        remove_all list
      elsif index >= 0 && index < list.size
        uninstall_gem list[index]
      else
        say "Error: must enter a number [1-#{list.size + 1}]"
      end
```

I would expect the command to exit silently or maybe exit with that "Error: must enter a number" message but not with an ugly nil error.
Maybe this scenario could be handled more gracefully by the tool?



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