[Fix #1980] Echo back missing namespace name on interactive eval

Note that this requires nREPL 0.4.3+.

See
nrepl/nrepl@e77945a
for the related nREPL change.

CHANGELOG.md

@@ -16,6 +16,7 @@
 * [#2305](https://github.com/clojure-emacs/cider/issues/2305): Make it possible to disable the REPL type auto-detection by customizing `cider-repl-auto-detect-type`.
 * [#2373](https://github.com/clojure-emacs/cider/issues/2373): Make it possible to configure the welcome message displayed in scratch buffers via `cider-scratch-initial-message`.
 * Add the ability to jump to the profiler buffer using `cider-selector`.
+* [#1980](https://github.com/clojure-emacs/cider/issues/1980): Echo back missing namespace name on interactive eval (requires nREPL 0.4.3+).
 
 ### Bugs fixed
 

nrepl-client.el

@@ -815,7 +815,10 @@ the corresponding type of response."
              (when (member "eval-error" status)
                (funcall (or eval-error-handler nrepl-err-handler)))
              (when (member "namespace-not-found" status)
-               (message "Namespace not found."))
+               ;; nREPL 0.4.3 started echoing back the name of the missing ns
+               (if ns
+                   (message "Namespace `%s' not found." ns)
+                 (message "Namespace not found.")))
              (when (member "need-input" status)
                (cider-need-input buffer))
              (when (member "done" status)