message: tolerate content types with no fields
diff: @@ -4,6 +4,7 @@ const find = require('./async-find');
  module.exports = class ContentType {
  constructor(model, allFields, dataSources, defaultDataSource, allGrants, authLog) {
  let fields = new Map();
  + if (model.relationships && model.relationships.fields) {
  for (let fieldRef of model.relationships.fields.data) {
  let field = allFields.get(fieldRef.id);
  if (!field) {
  @@ -14,6 +15,7 @@ module.exports = class ContentType {
  }
  fields.set(fieldRef.id, field);
  }
  + }
  // type and id fields are always implicitly present
  fields.set('type', allFields.get('type'));
  