[beduldul]

RichText.de_json catches resolution failures and falls back to the string, but the guard misses ValueError:

>>> types.RichText.de_json('{"type": "bold", "text": 5}')
ValueError: json_type should be a json dict or string.

That error comes from check_json, reached through RichTextBold.de_json → RichText.de_json(5). The except (KeyError, TypeError, AttributeError) in de_json does not catch it, so a payload shaped like RichText but holding a scalar crashes the caller. Before that fix it raised too; the guard only ever covered missing keys.

What this changes

Resolution failures fall back to plain text at the two places that can raise:

• the parsed-dict path in de_json, which now catches ValueError as well;
• a new RichText._resolve, used for the nested text of every RichText* subclass, which rejects a nested value that is not a str, list or dict.

_resolve also rejects a nested value that does not resolve to a single RichText. Without that, {"type": "bold", "text": {"type": "not_a_richtext"}} built a RichTextBold with text=None, and to_dict() on it produced a payload Telegram rejects. Same for text: [], which kept a list where one RichText is expected.

The 22 subclasses that called RichText.de_json(obj['text']) call cls._resolve(obj['text']) now, so the rule lives in one place instead of being repeated per class.

UNRESOLVED is a class attribute, not a module global, so nothing new appears in telebot.types.

What stays as it is

• ValueError from a top-level dict still propagates. A dict that cannot be parsed at all is a caller mistake, not text that arrived from Telegram.
• Every payload from "text" field disappears when using 'pre' format with language set to json in a rich message #2646 and fix(types): keep plain JSON text in RichBlockPreformatted #2647 behaves the same: {"foo": "bar"}, [56], {}, {"a": [1, 2]}, {"type": "not_a_richtext"} and a real serialized RichText all deserialize as before.
• mention and hashtag return the string unchanged. That is existing behaviour (_from_dict has no branch for either type, and RichTextMention/RichTextHashtag exist as classes but are never dispatched), not something this PR changes.

Tests

Five cases in tests/test_types.py:

• a nested text of 5, 1.5, true, false stays plain text, both through RichText.de_json and through RichBlockPreformatted;
• an unknown nested type does not build a parent object;
• a dict input that cannot resolve comes back untouched;
• every RichText* type survives 5, true and [] without raising.

Full suite: 327 passed, 72 skipped.

I also ran 175 type/value combinations and 500 random payloads against the change: no exception, and round-trip de_json → to_dict is unchanged for valid input.

Python 3.12.3, macOS 27.2.

Checklist:

• I added/edited example on new feature/change (if exists)
• My changes won't break backward compatibility
• I made changes both for sync and async