bug: Trying to append null for optional fields in JSON schema helpers should only warn, not crash the tap

[edgarrmondragon]

Singer SDK Version

0.31.1

Is this a regression?

• Yes

Python Version

NA

Bug scope

Taps (catalog, state, etc.)

Operating System

NA

Description

A schema like

{
  "properties": {
    "an_int": {"type": "integer"},
    "an_object": {"type": "object"},
    "an_array": {"type": "array"},
    "a_null": {"type": "null"},
    "anything": {},
  }
}

is perfectly valid under the JSON schema spec, so it should be supported by this library.

However, this fails when processing anything as part of a PropertiesList schema helper because it can't append null to a non-existing type key.

Code

No response