[Fix #2628] Don't try to font-lock multi-chunk results in the REPL

Also fixes #1971.

Author: bbatsov

CHANGELOG.md

@@ -22,6 +22,7 @@
 
 * [#2839](https://github.com/clojure-emacs/cider/pull/2839): Fix symbol-at-point on var-quoted symbols.
 * [#2807](https://github.com/clojure-emacs/cider/pull/2807): Fix require-repl-utils for shadow-cljs repls.
+* [#1971](https://github.com/clojure-emacs/cider/issues/1971), [#2628](https://github.com/clojure-emacs/cider/issues/2628): Don't try to font-lock multi-chunk results in the REPL.
 
 ## 0.24.0 (2020-02-15)
 

cider-util.el

@@ -313,6 +313,9 @@ This buffer is not designed to display anything to the user.  For that, use
         (with-current-buffer (cider--make-buffer-for-mode mode)
           (erase-buffer)
           (insert string)
+          ;; don't try to font-lock unbalanced Clojure code
+          (when (eq mode 'clojure-mode)
+            (check-parens))
           (font-lock-fontify-region (point-min) (point-max))
           (buffer-string))
       string)))
@@ -329,7 +332,11 @@ Unless you specify a BUFFER it will default to the current one."
 
 (defun cider-font-lock-as-clojure (string)
   "Font-lock STRING as Clojure code."
-  (cider-font-lock-as 'clojure-mode string))
+  ;; If something goes wrong (e.g. the code is not balanced)
+  ;; we simply return the string.
+  (condition-case nil
+      (cider-font-lock-as 'clojure-mode string)
+    (error string)))
 
 ;; Button allowing use of `font-lock-face', ignoring any inherited `face'
 (define-button-type 'cider-plain-button