Errors with entity backend methods

[alexkreidler]

Describe the bug
There are two errors that happen when creating a backend method.

To Reproduce
I have some code like this:

import { BackendMethod, Entity, EntityBase, Fields } from 'remult';

@Entity('page_group', { allowApiCrud: true })
export class PageGroup extends EntityBase {
  @Fields.uuid()
  id!: string;

  @Fields.date()
  created_at!: Date;

  @Fields.date()
  updated_at!: Date;

  @Fields.uuid()
  owner_id!: string;

  @Fields.string()
  name = '';

  @Fields.string()
  frequency = 'once';

  @Fields.boolean()
  js_rendered = true;

  @BackendMethod({ allowed: true })
  toggleCompleted() {
    // this.frequency = this.frequency === 'once' ? 'daily' : 'once'
    // await this.save()
  }
}

I originally had the commented out code active, and then tested with it commented out. I then got the first error shown below when sending a JSON object like { "args": [] } or { "args": ["string"] }, and the second error when removing args and sending an empty object {} or no body.

server started at http://0.0.0.0:3000
sqlite does not support inserting default values. Set the `useNullAsDefault` flag to hide this warning. (see docs https://knexjs.org/guide/query-builder.html#insert).
Ensure Schema: 22.764ms
{
  message: "Cannot read properties of undefined (reading 'isNewRow')",
  stack: [
    "TypeError: Cannot read properties of undefined (reading 'isNewRow')",
    '    at Object.<anonymous> (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/remult@0.21.1/node_modules/remult/src/server-action.js:285:72)',
    '    at step (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/tslib@2.6.0/node_modules/tslib/tslib.js:195:27)',
    '    at Object.next (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/tslib@2.6.0/node_modules/tslib/tslib.js:176:57)',
    '    at fulfilled (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/tslib@2.6.0/node_modules/tslib/tslib.js:166:62)'
  ],
  url: '/api/page_group/toggleCompleted',
  method: 'POST'
}
/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/remult@0.21.1/node_modules/remult/src/server-action.js:266
                                    d.args = d.args.map(function (x) { return isCustomUndefined(x) ? undefined : x; });
                                                    ^
TypeError: Cannot read properties of undefined (reading 'map')
    at Object.<anonymous> (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/remult@0.21.1/node_modules/remult/src/server-action.js:266:53)
    at step (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/tslib@2.6.0/node_modules/tslib/tslib.js:195:27)
    at Object.next (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/tslib@2.6.0/node_modules/tslib/tslib.js:176:57)
    at /home/alex/c2/magiscrape/backend2/node_modules/.pnpm/tslib@2.6.0/node_modules/tslib/tslib.js:169:75
    at new Promise (<anonymous>)
    at Object.__awaiter (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/tslib@2.6.0/node_modules/tslib/tslib.js:165:16)
    at /home/alex/c2/magiscrape/backend2/node_modules/.pnpm/remult@0.21.1/node_modules/remult/src/server-action.js:260:257
    at RemultServerImplementation.<anonymous> (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/remult@0.21.1/node_modules/remult/server/expressBridge.js:655:58)
    at step (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/tslib@2.6.0/node_modules/tslib/tslib.js:195:27)
    at Object.next (/home/alex/c2/magiscrape/backend2/node_modules/.pnpm/tslib@2.6.0/node_modules/tslib/tslib.js:176:57)
 ELIFECYCLE  Command failed with exit code 1.

Expected behavior
The function should be called without any problems

Desktop (please complete the following information):

• OS: Ubuntu 20.04
• Browser: Firefox
• Version: ^0.21.1

[yoni-rapoport]

As opposed to static BackendMethods, instance BackendMethods (such as this one) require additional entity instance data in the request. In this case, the JSON object you send should look like this:

{
    "rowInfo": {
        "data": { },
        "isNewRow": false,
        "wasChanged": false,
        "id": "<THE-UUID>"
    }
}

This is unfortunately not documented in the OpenAPI spec exported by Remult so please leave the issue open so we can fix that.