Thread:Extension talk:VisualEditor/TypeError: Expecting a function in instanceof check, but got undefined

I updated to 1.25wmf8, parsoid master, VE master. Special:Version shows everything's installed. Parsoid is running. When I go to click on the "Edit" link to evoke VE the content dims and the loading bar appears. Editor never actually loads.

Parsoid logs show: localhost/Test_Entry?oldid=84453 started parsing localhost/Test_Entry?oldid=84453 completed parsing in 536 ms

Console in Chrome shows:

Error column: 1390 line: 193 message: "undefined is not a valid argument for 'instanceof' (evaluating 'targetFn.prototype instanceof originFn')" sourceURL: " https://my-server.com/w/load.php?debug=false&lang=en&modules=ext.echo.base%2Coverlay%7Cext.echo.overlay.init% ... stack: "inheritClass@ https://my-server.com/w/load.php?debug=false&lang=en&modules=ext.echo.base%2Coverlay%7Cext.echo.overlay.init%7Cext.gadget.HotCat%7C ... __proto__: Error