fix: crash when using TouchBarScrubber arrow button (#30680)

Co-authored-by: Shelley Vohr <shelley.vohr@gmail.com>
electron · Aug 25, 2021 · 5d98e5e · 5d98e5e
1 parent 251e7bb
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Showing 2 changed files with 5 additions and 2 deletions.
diff --git a/docs/api/touch-bar-scrubber.md b/docs/api/touch-bar-scrubber.md
@@ -14,7 +14,7 @@ Process: [Main](../glossary.md#main-process)
     * `highlightedIndex` Integer - The index of the item the user touched.
   * `selectedStyle` String (optional) - Selected item style. Can be `background`, `outline` or `none`. Defaults to `none`.
   * `overlayStyle` String (optional) - Selected overlay item style. Can be `background`, `outline` or `none`. Defaults to `none`.
-  * `showArrowButtons` Boolean (optional) - Defaults to `false`.
+  * `showArrowButtons` Boolean (optional) - Whether to show arrow buttons. Defaults to `false` and is only shown if `items` is non-empty.
   * `mode` String (optional) - Can be `fixed` or `free`. The default is `free`.
   * `continuous` Boolean (optional) - Defaults to `true`.
 

diff --git a/shell/browser/ui/cocoa/electron_touch_bar.mm b/shell/browser/ui/cocoa/electron_touch_bar.mm
@@ -735,7 +735,10 @@ - (void)updateScrubber:(NSCustomTouchBarItem*)item
 
   bool showsArrowButtons = false;
   settings.Get("showArrowButtons", &showsArrowButtons);
-  scrubber.showsArrowButtons = showsArrowButtons;
+  // The scrubber will crash if the user tries to scroll
+  // and there are no items.
+  if ([self numberOfItemsForScrubber:scrubber] > 0)
+    scrubber.showsArrowButtons = showsArrowButtons;
 
   std::string selectedStyle;
   std::string overlayStyle;