How to remove empty yaml properties?

[szfkamil]

I need to remove all properties of YAML in markdown files that have empty values recursively in a directory.

Note: copied from Stack Overflow, as I could not a solution for weeks on there.

Before:

---
aliases:
cssclasses:
  - rss
tags: 
---

After:

---
cssclasses:
  - rss
---

It should remove the entire line no matter what object type it is: array, map, etc.

I currently tried, based another question to run the following:

yq -i 'del(.. | select(tag == "!!seq" and length == 0))' Hello.md and also replacing !!seq with !!map

$ yq -i 'del(.. | select(tag == "!!map" and length == 0))' Hello.md
---
aliases:
cssclasses:
  - rss
tags:
---

However, the command did not anything.

I also tried the first answer to this question (yq 'del(.. | select(. == ~))' Hello.md), but the command ends up eating up the bottom --- at all times which removes denotation of YAML e.g.

---
aliases:
cssclasses:
  - rss
tags: