Fix IEx.__break__!/3 fallback clause arity

[AlexGx]

Before

iex> break! 123
** (FunctionClauseError) no function clause matching in IEx.__break__!/3    
    
    The following arguments were given to IEx.__break__!/3:
...

After

iex> break! 123
** (ArgumentError) unknown expression to break on, expected one of:

  * Mod.fun/arity, such as: URI.parse/1
  * Mod.fun(arg1, arg2, ...), such as: URI.parse(_)
  * Mod.fun(arg1, arg2, ...) when guard, such as: URI.parse(var) when is_binary(var)

Got 123

Changes

• IEx.__break__!/3 fix arity
• test added

[josevalim]

💚 💙 💜 💛 ❤️