Summary

pickSchemaDialect is a module-level function but references this.loadSchema(s) (line 1338), where this is undefined in strict mode. This causes a TypeError when resolving schemas with custom (non-standard) $schema URIs that require loading the meta-schema to infer the base dialect.

Root cause: The function was introduced as part of #1166 (Support JSON Schema 2019 and 2020). It lives at module scope but uses this as if it were a class method.

Fix: Add an optional loadSchema callback parameter. The caller in resolveSchemaContent passes this.loadSchema.bind(this) through a closure variable. When loadSchema is not provided, the function returns undefined for unknown dialects instead of crashing.

Changed lines: +9/-3 in yamlSchemaService.ts

Reproduction

Any schema with a custom $schema URI that is not one of the well-known drafts triggers the bug:

{
  "$schema": "https://example.com/my-custom-meta-schema/v1",
  "type": "object",
  "properties": { "name": { "type": "string" } }
}

Also affects schemas embedding K8s definitions with "$schema": "http://json-schema.org/schema#" in nested $defs.

Test plan

• New test pickSchemaDialect.test.ts with 4 test cases:
  • Custom $schema URI does not throw TypeError
  • Known draft URIs still work (draft-07, 2020-12)
  • Nested $schema on sub-definitions does not crash
• All 1229 existing + new tests pass (0 failing, 5 pending — all pre-existing Windows-only skips)