I found a bug in clj-kondo in that it doesn't report a class name like Exception or String in a .cljc file when used in the :cljs branch and also not when used in .cljs files. Now the question is, should cases like:

(defn foo ^String [x] x)

It will make writing .cljc files a bit more convenient if clj-kondo would ignore it for the CLJS side too (since the compiler doesn't complain, you will get away with less reader conditionals)