fix for when the position doesn't have visible parens and has mismatched invisible parens

Author: rfindler

gui-lib/framework/private/color.rkt

@@ -953,42 +953,47 @@ added get-regions
            (define invisible-paren-count (+ invisible-paren-opens invisible-paren-closes))
            (define-values (outermost-start outermost-end error-outermost)
              (send (lexer-state-parens ls) match-forward (- start (lexer-state-start-pos ls)) #:invisible invisible-paren-count))
-           (let loop ([invisible-paren-count invisible-paren-count]
-                      [end-position outermost-end]
-                      [depth depth]
-                      [enclosing-highlight #f])
-             (when (< depth (vector-length paren-colors))
-               (define color (vector-ref paren-colors depth))
-               (cond
-                 [(zero? invisible-paren-count)
-                  (define-values (start-inner end-inner error-inner)
-                    (send (lexer-state-parens ls) match-forward (- start (lexer-state-start-pos ls))))
-                  (when (or (not (zero? invisible-paren-opens))
-                            (not (zero? invisible-paren-closes))
-                            start-inner)
-                    (cond
-                      [start-inner
-                       (seq-loop (+ start-inner 1) (- end-inner 1) (+ depth 1))
-                       (seq-loop (+ end-inner 1) (- end-position 1) depth)]
-                      [else
-                       (seq-loop (+ outermost-start 1) (- outermost-end 1) depth)]))
-                  (unless error-inner
-                    (when (and start-inner end-inner)
-                      (highlight ls start-inner end-inner caret-pos color priority)))]
-                 [else
-                  (define-values (start-inner end-inner error-inner)
-                    (send (lexer-state-parens ls) match-forward
-                          (- start (lexer-state-start-pos ls))
-                          #:invisible invisible-paren-count))
-                  (unless error-inner
-                    (cond
-                      [(equal? enclosing-highlight (cons start-inner end-inner))
-                       (loop (- invisible-paren-count 1) end-inner depth enclosing-highlight)]
-                      [else
-                       (seq-loop (+ end-inner 1) (- end-position 1) depth)
-                       (loop (- invisible-paren-count 1) end-inner (+ depth 1) (cons start-inner end-inner))
-                       (highlight ls start-inner end-inner caret-pos color priority)]))])))
-           outermost-end]
+           (cond
+             [(and outermost-start (not error-outermost))
+              (let loop ([invisible-paren-count invisible-paren-count]
+                         [end-position outermost-end]
+                         [depth depth]
+                         [enclosing-highlight #f])
+                (when (< depth (vector-length paren-colors))
+                  (define color (vector-ref paren-colors depth))
+                  (cond
+                    [(zero? invisible-paren-count)
+                     (define-values (start-inner end-inner error-inner)
+                       (send (lexer-state-parens ls) match-forward (- start (lexer-state-start-pos ls))))
+                     (when (or (not (zero? invisible-paren-opens))
+                               (not (zero? invisible-paren-closes))
+                               start-inner)
+                       (cond
+                         [start-inner
+                          (seq-loop (+ start-inner 1) (- end-inner 1) (+ depth 1))
+                          (seq-loop (+ end-inner 1) (- end-position 1) depth)]
+                         [else
+                          (seq-loop (+ outermost-start 1) (- outermost-end 1) depth)]))
+                     (unless error-inner
+                       (when (and start-inner end-inner)
+                         (highlight ls start-inner end-inner caret-pos color priority)))]
+                    [else
+                     (define-values (start-inner end-inner error-inner)
+                       (send (lexer-state-parens ls) match-forward
+                             (- start (lexer-state-start-pos ls))
+                             #:invisible invisible-paren-count))
+                     (unless error-inner
+                       (cond
+                         [(equal? enclosing-highlight (cons start-inner end-inner))
+                          (loop (- invisible-paren-count 1) end-inner depth enclosing-highlight)]
+                         [start-inner
+                          (seq-loop (+ end-inner 1) (- end-position 1) depth)
+                          (loop (- invisible-paren-count 1) end-inner (+ depth 1) (cons start-inner end-inner))
+                          (highlight ls start-inner end-inner caret-pos color priority)]
+                         [else
+                          (loop (- invisible-paren-count 1) end-inner (+ depth 1) enclosing-highlight)]))])))
+              outermost-end]
+             [else #f])]
           [else #f]))
 
       (single-spot-loop orig-start 0)