[Fix #2993] Eval require and in-ns separately in cider-repl-set-ns (#2994)

Turns out `require` and `in-ns` are special forms in ClojureScript and they can't be combined in a `do`.

Author: tomdl89

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Bugs fixed
 
+* [#2993](https://github.com/clojure-emacs/cider/issues/2993): Fix bug where calling `cider-repl-set-ns` for a cljs ns when `cider-repl-require-ns-on-set` is `t` would fail
 * [#2983](https://github.com/clojure-emacs/cider/issues/2983): update signal description in nrepl server sentinel as a workaround for emacs bug #46284 affecting v27.1 on windows
 * [#2941](https://github.com/clojure-emacs/cider/issues/2941): Use main args in alias for clojure cli
 * [#2953](https://github.com/clojure-emacs/cider/issues/2953): Don't font-lock function/macro vars as vars.

cider-repl.el

@@ -1207,9 +1207,9 @@ command will prompt for the name of the namespace to switch to."
     (user-error "No namespace selected"))
   (cider-map-repls :auto
     (lambda (connection)
-      (cider-nrepl-request:eval (if cider-repl-require-ns-on-set
-                                    (format "(do (require '%s) (in-ns '%s))" ns ns)
-                                  (format "(in-ns '%s)" ns))
+      (when cider-repl-require-ns-on-set
+        (cider-nrepl-sync-request:eval (format "(require '%s)" ns) connection))
+      (cider-nrepl-request:eval (format "(in-ns '%s)" ns)
                                 (cider-repl-switch-ns-handler connection)))))