Reader functions do not complain or error for arity

ClojureScript:

```
cljs.user=> (#(prn %) 1 2)
1
cljs.user=> (#(prn %1 %2) 1)
1 nil
```

Clojure:

```
user=> (#(prn %) 1 2)
ArityException Wrong number of args (2) passed to: user$eval2$fn  clojure.lang.AFn.throwArity (AFn.java:437)
user=> (#(prn %1 %2) 1)
ArityException Wrong number of args (1) passed to: user$eval8$fn  clojure.lang.AFn.throwArity (AFn.java:437)
```
