Odd JS console error in firefox web developer (about chrome though...?)

Error: [Exception... "'JavaScript component does not have a method named: "handleEvent"' when calling method: [nsIDOMEventListener::handleEvent]"  nsresult: "0x80570030 (NS_ERROR_XPC_JSOBJECT_HAS_NO_FUNCTION_NAMED)"  location: "JS frame :: chrome://global/content/bindings/popup.xml :: hidePopup :: line 108"  data: no]
Source File: chrome://global/content/bindings/popup.xml
Line: 108

Anyone ever see开发者_StackOverflow社区n this? Any idea where it could be coming from?

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Don't upgrade. With an upgrade from Mozilla 4.6 you may see this line below before it crashes:

Script: chrome://browser/content/tabbrowser.xml:1636