Uncaught TypeError: Cannot read property 'indexOf' of null
    at Object.attrObserver (content.js:formatted:538)
    at MutationObserver.<anonymous> (content.js:formatted:3005)
attrObserver @ content.js:formatted:538
(anonymous) @ content.js:formatted:3005
attributes (async)
setValueForStyles @ app.bundle.js:51193
updateDOMProperties @ app.bundle.js:52277
updateProperties$1 @ app.bundle.js:52633
commitUpdate @ app.bundle.js:53740
commitWork @ app.bundle.js:47805
commitAllHostEffects @ app.bundle.js:48859
callCallback @ app.bundle.js:37551
invokeGuardedCallbackDev @ app.bundle.js:37589
invokeGuardedCallback @ app.bundle.js:37638
commitRoot @ app.bundle.js:49010
completeRoot @ app.bundle.js:49953
performWorkOnRoot @ app.bundle.js:49903
performWork @ app.bundle.js:49821
performSyncWork @ app.bundle.js:49798
requestWork @ app.bundle.js:49698
scheduleWorkImpl @ app.bundle.js:49573
scheduleWork @ app.bundle.js:49533
enqueueSetState @ app.bundle.js:44095
Component.setState @ app.bundle.js:35912
onStateChange @ app.bundle.js:14368
dispatch @ app.bundle.js:13755
dispatch @ VM9961:1
(anonymous) @ app.bundle.js:56450
dispatch @ app.bundle.js:14097
(anonymous) @ app.bundle.js:9673
setTimeout (async)
(anonymous) @ app.bundle.js:9666
setTimeout (async)
(anonymous) @ app.bundle.js:9650
(anonymous) @ app.bundle.js:56447
dispatch @ VM9961:1
(anonymous) @ app.bundle.js:13983
Draggable._this.onLift @ app.bundle.js:11941
(anonymous) @ app.bundle.js:10992
startDragging @ app.bundle.js:10914
fn @ app.bundle.js:10991