Every browser has its quirks on errors. At least IE will give you stack info from window.onerror even without a try/catch, although they didn't get the file nam

Every browser has its quirks on errors. At least IE will give you stack info from window.onerror even without a try/catch, although they didn't get the file name right until IE8. The "line 0" errors are often due to eval scripts where there is no source file, it could even be something like a bad JSON string being passed to a JSON.parse shim.