command

$ ruby t.rb
OK

$ ./tmp/mruby/bin/mruby t.rb
not found class A
t.rb:11: uninitialized constant A (NameError)

$ ./tmp/mruby/bin/mruby t2.rb
OK

t.rb

class A
end

module Kernel
  def hoge
    A  # found class A
    begin
      ['a'].each do |i|
        A  # not found class A
        puts "OK"
      end
    rescue NameError => e
      puts "not found class A"
      p e
    end
  end
end

hoge

t2.rb

class A
end

module Hoge
  def hoge
    A  # found class A
    begin
      ['a'].each do |i|
        A  # not found class A
        puts "OK"
      end
    rescue NameError => e
      puts "not found class A"
      p e
    end
  end
end

include Hoge

hoge