fix typo, NUL -> NULL


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48312 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
ChangeLog: not a typo [ci skip]

* ChangeLog: NUL means a name of ASCII '\0', not a NULL pointer.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48313 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_exception.rb: more tests

* test/ruby/test_exception.rb: more tests for catch and throw.
  catch but no throw, autogenerated tag, and uncaught throw.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48314 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
vm_eval.c: UncaughtThrowError

* vm_eval.c (rb_throw_obj): throw UncaughtThrowError instead of
  ArgumentError.  [Feature #10480]