readRichText

A shape's label as a rich-text document — the reader every other label read goes through.

A record can carry either spelling, or both, or both *disagreeing*: a v5 writer sets props.richText and leaves props.text at its default, a pre-v5 writer does the reverse, and a partial update touches one without the other. So the rule is stated once, here:

1. a rich-text document that actually says something wins — it is the canonical spelling and the only one that can carry formatting; 2. otherwise a non-empty props.text is lifted into a document; 3. otherwise the label is empty, and the stored document (if any) is kept so an empty-but-structured document survives a round trip.

An empty label is one empty paragraph, which is what this format spells "nothing typed yet" — never a document with no content at all.