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            <b><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - REGRESSION: Layout Test storage/indexeddb/detached-iframe.html is a flaky crash"
   href="https://bugs.webkit.org/show_bug.cgi?id=180174#c4">Comment # 4</a>
              on <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - REGRESSION: Layout Test storage/indexeddb/detached-iframe.html is a flaky crash"
   href="https://bugs.webkit.org/show_bug.cgi?id=180174">bug 180174</a>
              from <span class="vcard"><a class="email" href="mailto:joepeck@webkit.org" title="Joseph Pecoraro <joepeck@webkit.org>"> <span class="fn">Joseph Pecoraro</span></a>
</span></b>
        <pre>The crash looks like a null Frame:

<span class="quote">> Exception Type:        EXC_BAD_ACCESS (SIGSEGV)
> Exception Codes:       KERN_INVALID_ADDRESS at 0x0000000000000040

> ...

> Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
> 0   com.apple.WebCore              0x0000000450402a8c WebCore::Frame::page() const + 12 (Frame.h:373)
> 1   com.apple.WebCore              0x0000000451830325 WebCore::InspectorInstrumentation::instrumentingAgentsForFrame(WebCore::Frame&) + 21 (InspectorInstrumentation.h:1431)
> 2   com.apple.WebCore              0x0000000452480116 WebCore::InspectorInstrumentation::didDispatchPostMessage(WebCore::Frame&, WebCore::TimerBase&) + 54 (InspectorInstrumentation.h:731)
> 3   com.apple.WebCore              0x000000045247fe57 WebCore::DOMWindow::postMessageTimerFired(WebCore::PostMessageTimer&) + 551 (DOMWindow.cpp:973)</span >

Coming from:

<span class="quote">>    void DOMWindow::postMessageTimerFired(PostMessageTimer& timer)
>    {
>        if (!document() || !isCurrentlyDisplayedInFrame())
>            return;</span >
>
<span class="quote">>        ...</span >
>
<span class="quote">>        InspectorInstrumentation::willDispatchPostMessage(*m_frame, timer);</span >
>
<span class="quote">>        dispatchEvent(timer.event(*document()));</span >
>
<span class="quote">>        InspectorInstrumentation::didDispatchPostMessage(*m_frame, timer);
>    }</span >

So my guess is `m_frame` is nullptr by didDispatchPostMessage time (and presumably wasn't at willDispatchPostMessage time).</pre>
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