core.js:647 Handler of component is invalid -> TypeError: Cannot read property 'flow' of undefined

[#1]

Recently we see these errors coming up over and over again in Author when designer templates, forms, ...

Any clue where this is coming from. core.js is not a script file we can read easily.

[#2]

@Eric_Stricker When exactly you are observing this issue? Please share the logs/snippet of log for review.

[#3]

@Rakhi_Sukhadeve 

The issue is noticed in the browser when doing development. 

We normally use Chrome for development (Version 83.0.4103.97 (Official Build) (64-bit), this morning I tried Firefox and the issue does not occur in Firefox. 

I happen when you want to edit a template or adaptive form or site, just anything once you go into edit mode it will appear. Sometimes 1 error, sometimes 3, occasionally the error appears 5 times at one go.

[#4]

Copy-past of the image text into plain text 

granite.js:259 [Deprecation] Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check https://xhr.spec.whatwg.org/.
structure.html:1 [DOM] Found 2 elements with non-unique id #editor-styleselector-form: (More info: https://goo.gl/9p2vKq)

6core.js:647 Handler of component is invalid -> TypeError: Cannot read property 'flow' of undefined
at eval (eval at ns.util.sanitizeCQHandler (https://localhost:4502/libs/cq/gui/components/authoring/editors/clientlibs/core.js:272:94), <anonymous>:1:14)
at Object.ns.util.sanitizeCQHandler (https://localhost:4502/libs/cq/gui/components/authoring/editors/clientlibs/core.js:272:94)
at String.<anonymous> (https://localhost:4502/libs/cq/gui/components/authoring/editors/clientlibs/core.js:322:337)
at Function.each (https://localhost:4502/etc.clientlibs/clientlibs/granite/jquery.js:377:19)
at constructor._loadConfig (https://localhost:4502/libs/cq/gui/components/authoring/editors/clientlibs/core.js:321:277)
at constructor.updateConfig (https://localhost:4502/libs/cq/gui/components/authoring/editors/clientlibs/core.js:323:64)
at Object.<anonymous> (https://localhost:4502/libs/cq/gui/components/authoring/editors/clientlibs/core.js:922:131)
at fire (https://localhost:4502/etc.clientlibs/clientlibs/granite/jquery.js:3233:31)
at Object.fireWith [as resolveWith] (https://localhost:4502/etc.clientlibs/clientlibs/granite/jquery.js:3363:7)
at done (https://localhost:4502/etc.clientlibs/clientlibs/granite/jquery.js:9841:14)
contexthub:442 Uncaught TypeError: Cannot read property 'externalize' of undefined
at contexthub:442
at contexthub:446
structure.html:94 Uncaught TypeError: window.injectContextHubUI is not a function
at structure.html:94
at structure.html:127
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