richTextToPlainText

Flatten a rich-text document to the plain string mocanvas stores in props.text.

The document is a tree of { type, content?, text? } nodes. text nodes contribute their string, hardBreak nodes a newline, top-level paragraphs are joined by newlines, and any other node is recursed into so unknown marks or wrappers still yield their text. unknownNodeTypes, when passed, collects the node types that were not understood.