Created attachment 295144 [details] crash log I get a lot of those crashes when interacting with Issues and Pull Requests on Github.com Actions on GitHub issues I often, but not always, get this crash: * assign an issue or pull request to one or multiple collaborators * assign tags to an issue or pull request * add a comment to an issue or pull request I think these crashes started to happen with Safari Technology Preview Release 16. The still happens with Release 18 (Safari 10.1, WebKit 12603.1.12) on macOS 10.12.1 (16B2555) Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0 com.apple.WebCore 0x000000010a6956b0 WebCore::ElementRuleCollector::matchHostPseudoClassRules(WebCore::MatchRequest&, WebCore::StyleResolver::RuleRange&) + 240 1 com.apple.WebCore 0x000000010a17f062 WebCore::ElementRuleCollector::matchAuthorRules(bool) + 194 2 com.apple.WebCore 0x000000010a17ede2 WebCore::ElementRuleCollector::matchAllRules(bool, bool) + 626 3 com.apple.WebCore 0x000000010b1a5004 WebCore::StyleResolver::styleForElement(WebCore::Element const&, WebCore::RenderStyle const*, WebCore::RuleMatchingBehavior, WebCore::RenderRegion const*, WebCore::SelectorFilter const*) + 932 4 com.apple.WebCore 0x000000010a68caf0 WebCore::Element::resolveStyle(WebCore::RenderStyle const*) + 96 5 com.apple.WebCore 0x000000010a60d297 WebCore::Document::styleForElementIgnoringPendingStylesheets(WebCore::Element&, WebCore::RenderStyle const*) + 71 6 com.apple.WebCore 0x000000010a690f58 WebCore::Element::resolveComputedStyle() + 696 7 com.apple.WebCore 0x000000010a1ca9a2 WebCore::Element::computedStyle(WebCore::PseudoId) + 194
rdar://problem/28990966
*** This bug has been marked as a duplicate of bug 165030 ***