Remote `$ref` in linked local `$ref` throws `ArgumentError`

[Dampfwalze]

When a $ref refers to a local definition (for example: "$ref": "#$defs/someDef"), the _baseResolvePaths() step tries to resolve that local path, while assuming all references have been resolved (using resolvePath()). But this assumption is wrong. Because the target of that path might still have a remote source:

final schema = await JsonSchema.createAsync({
  r"$schema": "https://json-schema.org/draft/2020-12/schema",
  r"$id": "test.schema.json",
  r'$defs': {
    'geographical-location': {
      r'$ref': 'https://example.com/geographical-location.schema.json',
    },
  },
  'type': 'array',
  'items': {r'$ref': r'#/$defs/geographical-location'},
}, refProvider: refProvider);

throws:

ArgumentError ("Invalid argument(s): Failed to get schema for path because the schema file (https://example.com/geographical-location.schema.json#) could not be found. Unable to resolve path https://example.com/geographical-location.schema.json")

This is where the assumption is made:

json_schema/lib/src/json_schema/json_schema.dart

Lines 459 to 462 in dc39865

	// Resolve sub schema of fetched schema if a fragment was included.
	if (resolvedSuccessfully && schemaUri.fragment.isNotEmpty) {
	localSchema?.resolvePath(Uri.parse('#${schemaUri.fragment}'));
	}

But the result of that operation is not used at all. Is this simply a validation step, or can this be omitted? When removing this part, the example works fine.

[kyleferguson-wk]

Hello @Dampfwalze! I think one potential workaround here in this case could be to just use the $ref directly. As far as the issue being addressed here, I can't guarantee we'll be able to get to it quickly. That being said if you want to put up a PR with a fix we'd be more than happy to review it!