[eval] Fix broken stacktrace response when C-c C-p throws an exception

CHANGELOG.md

@@ -9,6 +9,7 @@
 ### Bugs fixed
 
 - [#3832](https://github.com/clojure-emacs/cider/issues/3832): Fix nrepl--eval-request sending duplicate info.
+- [#3837](https://github.com/clojure-emacs/cider/issues/3837): Fix broken stacktrace response when C-c C-p throws an exception.
 
 ## 1.19.0 (2025-07-10)
 

cider-eval.el

@@ -884,10 +884,10 @@ COMMENT-POSTFIX is the text to output after the last line."
  (lambda (_buffer warning)
  (setq res (concat res warning))))))
 
-(defun cider-popup-eval-handler (&optional buffer _bounds _source-buffer)
+(defun cider-popup-eval-handler (&optional buffer _bounds source-buffer)
  "Make a handler for printing evaluation results in popup BUFFER,
 _BOUNDS representing the buffer bounds of the evaled input,
-and _SOURCE-BUFFER the original buffer
+and SOURCE-BUFFER the original buffer
 
 This is used by pretty-printing commands."
  ;; NOTE: cider-eval-register behavior is not implemented here for performance reasons.
@@ -907,15 +907,15 @@ This is used by pretty-printing commands."
  ;; done handler:
  nil
  ;; eval-error handler:
- (lambda (buffer)
+ (lambda (_buffer)
  (when (and (buffer-live-p chosen-buffer)
  (member (buffer-name chosen-buffer)
  cider-ancillary-buffers))
  (with-selected-window (get-buffer-window chosen-buffer)
  (cider-popup-buffer-quit-function t)))
  ;; also call the default nrepl-err-handler, so that our custom behavior doesn't void the base behavior:
  (when nrepl-err-handler
- (funcall nrepl-err-handler buffer)))
+ (funcall nrepl-err-handler source-buffer)))
  ;; content type handler:
  nil
  ;; truncated handler: