[REQUEST] Filtering by tags with empty string value

[heguro]

Pledge
10000 sats

Is your feature request related to a problem? Please describe.
I wanted to search for events having tag ["d", ""] by using the filter {"#d": [""]}.
Currently this is rejected with the error invalid: "[2].#d[0]" is not allowed to be empty by this line (I think):

https://github.com/Cameri/nostream/blob/f23740073f6b59b230157528376a89ca44af3f27/test/unit/schemas/event-schema.spec.ts#L123

Describe the solution you'd like
Support for filtering tag value by "".

Additional context

• I could use this filter in nostr-rs-relay.
• You can see NIP-23 posts (kind:30023) and NIP-58 badges (kind:30009) having tag ["d", ""] at wss://nostr-pub.wellorder.net.
  • Send ["REQ", "subId", { "#d": [""] }] to the relay with Nostr Playground or other tool to see some cases.
• There was a bug that d tag of some badges created with non-English name become empty string in badges.page. This is fixed, but some badges with tag ["d", ""] have already been published.