It indeed appears to be unable to catch exceptions that happen in event handlers that aren't attached with jQuery or directly in <script/> tags not wrapped in .ready() events, which is interesting because doing so is totally possible: https://developer.mozilla.org/en-US/docs/DOM/window.onerror

There's an argument to be made for attaching event handlers any way besides using jQuery would be bad practice, but not waiting for .ready() to fire is totally normal for sites practicing Progressive Enhancement that put all the <script/> tags at the end of the <body/>.