Fix: ignore undefined values in schema properties

[veeceey]

Summary

This PR fixes issue #2578 where schemas with undefined property values (commonly from destructuring) cause ajv to throw a TypeError instead of ignoring them.

Before:

const ajv = new Ajv({strictSchema: false, validateSchema: false});
const schema = {
  type: 'object',
  properties: {
    foo: {type: 'string'},
    bar: undefined  // From destructuring or conditional logic
  }
};
ajv.validate(schema, {foo: 'test'}); // Throws: "Cannot convert undefined or null to object"

After:

ajv.validate(schema, {foo: 'test'}); // Returns: true (undefined properties ignored)

Changes

• Modified allSchemaProperties() in lib/vocabularies/code.ts to filter out undefined values
• Added comprehensive test coverage for various scenarios with undefined schema properties

Test Coverage

The fix includes tests for:

• Basic undefined property handling
• Multiple undefined properties
• Validation still works correctly for defined properties
• Undefined values from destructuring scenarios

Manual Testing

Verified the fix handles:

• Single undefined properties
• Multiple undefined properties mixed with valid ones
• Validation errors still work correctly for defined properties
• Pattern properties with undefined values

Closes #2578

[veeceey]

gentle ping — would be great to get some eyes on this when possible