Rails script/console crashes when I press up button because of bug in readline

Question

This issue is intermittent, but pressing the up-arrow to get a previously entered command I'll get an error such as:

/Users/me/.rvm/gems/ruby-1.9.3-p194/gems/activesupport-2.3.14/lib/active_support/whiny_nil.rb:52:in `method_missing': undefined method `force_encoding' for nil:NilClass (NoMethodError)
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:3801:in `_rl_col_width'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:2944:in `update_line'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:3486:in `block in rl_redisplay'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:3481:in `each'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:3481:in `rl_redisplay'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:4618:in `_rl_internal_char_cleanup'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:4679:in `readline_internal_charloop'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:4743:in `readline_internal'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:4765:in `readline'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/readline.rb:40:in `readline'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/input-method.rb:115:in `gets'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:139:in `block (2 levels) in eval_input'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:273:in `signal_status'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:138:in `block in eval_input'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `call'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `buf_input'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:103:in `getc'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/slex.rb:205:in `match_io'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/slex.rb:75:in `match'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:286:in `token'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:262:in `lex'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:233:in `block (2 levels) in each_top_level_statement'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `loop'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `block in each_top_level_statement'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `catch'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `each_top_level_statement'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:155:in `eval_input'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:70:in `block in start'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:69:in `catch'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:69:in `start'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/bin/irb:16:in `<main>'

Looks like the issue is in readline? How to resolve the issue? According to bundle list I have this version of readline:

• rb-readline (0.4.2)

Update : New error after updating with rvm pkg install readline per answer:

>/Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:2730:in `[]': no implicit conversion from nil to integer (TypeError)
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:2730:in `update_line'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:3486:in `block in rl_redisplay'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:3481:in `each'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:3481:in `rl_redisplay'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:4618:in `_rl_internal_char_cleanup'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:4679:in `readline_internal_charloop'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:4743:in `readline_internal'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/rbreadline.rb:4765:in `readline'
    from /Users/me/.rvm/gems/ruby-1.9.3-p194/gems/rb-readline-0.4.2/lib/readline.rb:40:in `readline'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/input-method.rb:115:in `gets'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:139:in `block (2 levels) in eval_input'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:273:in `signal_status'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:138:in `block in eval_input'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `call'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `buf_input'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:103:in `getc'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/slex.rb:205:in `match_io'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/slex.rb:75:in `match'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:286:in `token'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:262:in `lex'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:233:in `block (2 levels) in each_top_level_statement'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `loop'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `block in each_top_level_statement'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `catch'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `each_top_level_statement'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:155:in `eval_input'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:70:in `block in start'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:69:in `catch'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/irb.rb:69:in `start'
    from /Users/me/.rvm/rubies/ruby-1.9.3-p194/bin/irb:16:in `<main>'

And I still get the old error, as well.

Answer 1

It's clearly a problem with rb-readline.

I usually install readline as an rvm package:

rvm pkg install readline

And don't use any readline specific stuff in my Gemfile.

You may also have a look at:

Problems with the rails console, RVM and readline

Answer 2

I encountered this today.

I believe that this occurs because readline is trying to parse some of the text on the console line. Some text doesn't play nicely.

So why the up key?

This happened to be after I pasted a load of 'stuff' to set a variable. I obviously got something wrong in that pasting because the console crashed.

What do all IT professionals do after something crashes? Try it again. Whats the quickest way to try the last command you wrote in the rails console? The up key.

A good work around for this is to simply not hit the up key or clear the history to remove the offending line.