Exception appears in markdown editor opened in modal window while adding product

[nstoliar-sc]

Meta-Info	Value
ExtProjectId	JCCMMN-01
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Exception appears in markdown editor opened in modal window while adding product. Problem exists in

react-markdown/src/client/components/PlainMarkdownInput/plugins/slate-autocomplete-plugin/AutocompleteWidget.js

Line 128 in 97ee0d5

if (selection.anchorNode) {