message: support relative URLs in field references
diff: @@ -41,7 +41,7 @@ export class Compiler {
  let schemaModule = await this.prepareSchema(cardSource, options);
  let meta = getMeta(options);
  - let fields = await this.lookupFieldsForCard(meta.fields);
  + let fields = await this.lookupFieldsForCard(meta.fields, cardSource.url);
  this.defineAssets(cardSource);
  @@ -182,11 +182,12 @@ export class Compiler {
  return await this.builder.define(cardSource.url, schemaLocalFilePath, JS_TYPE, code);
  }
  - private async lookupFieldsForCard(metaFields: FieldsMeta): Promise<CompiledCard['fields']> {
  + private async lookupFieldsForCard(metaFields: FieldsMeta, ownURL: string): Promise<CompiledCard['fields']> {
  let fields: CompiledCard['fields'] = {};
  for (let [name, { cardURL, type }] of Object.entries(metaFields)) {
  + let fieldURL = new URL(cardURL, ownURL).href;
  fields[name] = {
  - card: await this.builder.getCompiledCard(cardURL),
  + card: await this.builder.getCompiledCard(fieldURL),
  type,
  name,
  };
  