Avoid overlays and messages on stderr that is unrelated to exception handling

Fixes #3587

Author: vemv

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 - [#3605](https://github.com/clojure-emacs/cider/issues/3605): avoid `cider--error-phase-of-last-exception` recursive loop.  
 - [#3613](https://github.com/clojure-emacs/cider/issues/3613): adapt `cider-completion-context.el` to upstream changes in Compliment.  
+- [#3587](https://github.com/clojure-emacs/cider/issues/3587): avoid overlays and `message`s on stderr that is unrelated to exception handling.
 
 ## 1.13.0 (2024-01-14)
 

cider-eval.el

@@ -913,13 +913,16 @@ and the suffix matched by `cider-module-info-regexp'."
 (defun cider--maybe-display-error-as-overlay (phase err end)
   "Possibly display ERR as an overlay honoring END,
 depending on the PHASE."
-  (when (or
-         ;; if we won't show *cider-error*, because of configuration, the overlay is adequate because it compensates for the lack of info in a compact manner:
-         (not cider-show-error-buffer)
-         (not (cider-connection-has-capability-p 'jvm-compilation-errors))
-         ;; if we won't show *cider-error*, because of an ignored phase, the overlay is adequate:
-         (and cider-show-error-buffer
-              (member phase (cider-clojure-compilation-error-phases))))
+  (when (and (or
+              ;; if we won't show *cider-error*, because of configuration, the overlay is adequate because it compensates for the lack of info in a compact manner:
+              (not cider-show-error-buffer)
+              (not (cider-connection-has-capability-p 'jvm-compilation-errors))
+              ;; if we won't show *cider-error*, because of an ignored phase, the overlay is adequate:
+              (and cider-show-error-buffer
+                   (member phase (cider-clojure-compilation-error-phases))))
+             ;; Only show overlays for things that do look like an exception (#3587):
+             (or (string-match-p cider-clojure-runtime-error-regexp err)
+                 (string-match-p cider-clojure-compilation-regexp err)))
     ;; Display errors as temporary overlays
     (let ((cider-result-use-clojure-font-lock nil)
           (trimmed-err (funcall cider-inline-error-message-function err)))