peek-a-boo error message "Render Failed. See console for details."

After what I think is an update today, every time I go to a method-configuration I see the text
"Render Failed. See console for details." in red. Then, about a moment or two later, it goes away (so "peek-a-boo")

in the console I see

5compiled.js:2913 TypeError: Cannot read property 'call' of null
    at Function.<anonymous> (compiled.js:4770)
    at Function.cljs.core.apply.cljs$core$IFn$_invoke$arity$3 (compiled.js:784)
    at cljs.core.apply (compiled.js:782)
    at Function.dmohs.react.core.call_fn.cljs$core$IFn$_invoke$arity$variadic (compiled.js:2903)
    at dmohs.react.core.call_fn (compiled.js:2903)
    at t.render (compiled.js:2913)
    at c._renderValidatedComponentWithoutOwnerOrContext (compiled.js:25)
    at c._renderValidatedComponent (compiled.js:25)
    at c._updateRenderedComponent (compiled.js:25)
    at c._performComponentUpdate (compiled.js:25)
    at c.updateComponent (compiled.js:25)
    at c.performUpdateIfNecessary (compiled.js:25)
    at Object.performUpdateIfNecessary (compiled.js:27)

After the message goes away it does not seem to be a "blocker" for work.