Workflow failing with TypeError: Access to host class jetbrains.youtrack.workflow.model.Assertion is not allowed or does not exist

I'm attempting to modify @jetbrains/youtrack-spreadsheets-client (below). I added this statement:

const entities = require('@jetbrains/youtrack-scripting-api/entities');

which results in a runtime error:

TypeError: Access to host class jetbrains.youtrack.workflow.model.Assertion is not allowed or does not exist.

Can't imagine why I'd receive this error,

What I'm trying to accomplish is to to get the logged in user so I can set Author. Apparently there is no currentUser in the context so I was hoping (perhaps foolishly) to be able to get it via the entities interface.

Thanks for the help.

/**
 * Copyright JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

const ProjectFieldConverter = require('./project-field-converter');
const FieldConverter = require('./field-converter');
const Util = require('./util');
const entities = require('@jetbrains/youtrack-scripting-api/entities');

function getIssueFields(project, issue) {

  let theAuthor=null;
  FieldConverter.getConvertedFields(project, issue)
      .filter(field => {
        let fieldName = field.name;
        fieldName = fieldName.toLowerCase().replace(/ /g, '');
        if (fieldName === 'theauthor') {
            //theAuthor = entities.User.current;  
          //theAuthor = entities.User.findByLogin(field.value); 
        }
  });
  let ctx = Util.getCtx();
  
  let baseFields = {
    summary: '',
    description: '',
    created: new Date().toISOString(),
    updated: new Date().toISOString(),
    links: [],
    /*author: theAuthor,*/
   /* author: {
      login: ctx.currentUser.login,
      name: ctx.currentUser.name,
      type: 'user'
    },*/
    comments: [],
    attachments: [],
    tags: [],
    watchers: [],
    voters: []
  };

  let extraFields = [];

  FieldConverter.getConvertedFields(project, issue)
      .filter(field => {
        let fieldName = field.name;
        fieldName = fieldName.toLowerCase().replace(/ /g, '');

        let isReservedFieldTitle = !(fieldName !== 'description'
            && fieldName !== 'summary'
            && fieldName !== 'tags'
            && fieldName !== 'links'
            && fieldName !== 'attachments'
            && fieldName !== 'comments'
            && fieldName !== 'watchers'
            && fieldName !== 'created'
            && fieldName !== 'updated'
            && fieldName !== 'reporter'
            && fieldName !== 'issue id'
            && fieldName !== 'reporter'
            && fieldName !== 'project'
            && fieldName !== 'votes'
            && fieldName !== 'voters');

        if (isReservedFieldTitle) {
          switch (fieldName) {
            case 'summary':
            case 'description':
              field.name = fieldName;
              extraFields.push(field);
          }
          return false;
        } else {
          return true;
        }
      })
      .forEach(field => {
        let name = field.name;
        if (!(field.type === 'enum' || field.type === 'enum multi' || field.type === 'user')) {
          delete field.name;
          baseFields[name] = field;
        } else {
          switch (field.type) {
            case 'enum': {
              delete field.name;
              baseFields[name] = field;
              break;
            }
            case 'user': {
              let values = field.value;
              let result = [];
              if (values) {
                values.forEach(value => {
                  result.push({
                    multiValue: true,
                    type: 'user',
                    value: value
                  });
                });
                baseFields[name] = result;
              }
              break;
            }
            case 'enum multi': {
              let values = field.value;
              let result = [];
              if (values) {
                values.forEach(value => {
                  result.push({
                    multiValue: true,
                    type: 'enum',
                    value: value
                  });
                });
                baseFields[name] = result;
              }
              break;
            }
          }
        }
      });

  extraFields.forEach(field => baseFields[field.name] = field.value);

  return baseFields;
}

function getProjectFields(project) {
  let baseFields = [];

  ProjectFieldConverter.getConvertedProjectFields(project)
      .filter(field => {
        let fieldName = field.name;
        fieldName = fieldName.toLowerCase().replace(/ /g, '');

        return fieldName !== 'description'
            && fieldName !== 'summary'
            && fieldName !== 'tags'
            && fieldName !== 'links'
            && fieldName !== 'attachments'
            && fieldName !== 'comments'
            && fieldName !== 'watchers'
            && fieldName !== 'created'
            && fieldName !== 'updated'
            && fieldName !== 'author'
            && fieldName !== 'voters';
      })
      .forEach(field => {
        switch (field.type) {
          case 'enum multi': {
            delete field.type;
            field.type = 'enum';
            field.multiValue = true;
            baseFields.push(field);
            break;
          }
          case 'user': {
            field.multiValue = true;
            baseFields.push(field);
            break;
          }
          default: {
            baseFields.push(field);
          }
        }
      });

  return baseFields;
}

module.exports = {
  getIssueFields,
  getProjectFields
};