Fix indentation error in js.el

* lisp/progmodes/js.el (js--indent-in-array-comp): Wrap forward-sexp
call in condition-case.
* test/lisp/progmodes/js-tests.el (js-mode-indentation-error): New
test.

2 files changed, 20 insertions, 5 deletions

diff --git a/lisp/progmodes/js.el b/lisp/progmodes/js.el
index 6e313dc51b7..65325a8ffad 100644
--- a/lisp/progmodes/js.el
+++ b/lisp/progmodes/js.el
@@ -1986,11 +1986,16 @@ In particular, return the buffer position of the first `for' kwd."
         (js--forward-syntactic-ws)
         (if (looking-at "[[{]")
             (let (forward-sexp-function) ; Use Lisp version.
-              (forward-sexp)             ; Skip destructuring form.
-              (js--forward-syntactic-ws)
-              (if (and (/= (char-after) ?,) ; Regular array.
-                       (looking-at "for"))
-                  (match-beginning 0)))
+              (condition-case nil
+                  (progn
+                    (forward-sexp)       ; Skip destructuring form.
+                    (js--forward-syntactic-ws)
+                    (if (and (/= (char-after) ?,) ; Regular array.
+                             (looking-at "for"))
+                        (match-beginning 0)))
+                (scan-error
+                 ;; Nothing to do here.
+                 nil)))
           ;; To skip arbitrary expressions we need the parser,
           ;; so we'll just guess at it.
           (if (and (> end (point)) ; Not empty literal.
diff --git a/test/lisp/progmodes/js-tests.el b/test/lisp/progmodes/js-tests.el
index 99f5898525b..07e659af605 100644
--- a/test/lisp/progmodes/js-tests.el
+++ b/test/lisp/progmodes/js-tests.el
@@ -118,6 +118,16 @@ if (!/[ (:,='\"]/.test(value)) {
       ;; implementation not recognizing the comment example.
       (should-not (syntax-ppss-context (syntax-ppss))))))
 
+(ert-deftest js-mode-indentation-error ()
+  (with-temp-buffer
+    (js-mode)
+    ;; The bug previously was that requesting re-indentation on the
+    ;; "{" line here threw an exception.
+    (insert "const TESTS = [\n{")
+    (js-indent-line)
+    ;; Any success is ok here.
+    (should t)))
+
 (provide 'js-tests)
 
 ;;; js-tests.el ends here