custom endpoint

[Drs Mark Schonewille]

A programmer previously involved in my project --I'm replacing him-- has
created a custom endpoint (uploaded as a service through ArangoDB's web
interface). The custom endpoint seems to have been installed correctly.
I can do send a GET request and get a result, but I can't do POST
request. The error I get is either 401 or 404. Among other things, the
script is supposed to upload data to different collections and documents
at once. The script is executed by another script that was programmed in
LiveCode. The LiveCode script is fairly complicated, but it boild down
to a simple POST request as one may also perform using curl.

The log in ArangoDB's web interface shows a bunch of errors. Here's a
selection from those errors (question follows below):

[24213] at Tree.dispatch (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:135:7)
16 minutes ago
[24213] at dispatch (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:426:3)
16 minutes ago
[24213] at next (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:410:7)
16 minutes ago
[24213] at next (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:414:15)
16 minutes ago
[24213] at Middleware.
(C:\ProgramData\ArangoDB-apps\_db\key2publish\myshop\APP\index.js:23:3)
16 minutes ago
[24213] at c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\node\node_modules\lodash\lodash.js:10052:25
16 minutes ago
[24213] at next (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:410:7)
16 minutes ago
[24213] at next (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:412:15)
16 minutes ago
[24213] at Route._handler
(C:\ProgramData\ArangoDB-apps\_db\key2publish\myshop\APP\index.js:89:20)
16 minutes ago
[24213] at ArangoDatabase._executeTransaction (c:\Program
Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\arango-database.js:171:10)
16 minutes ago
[24213] via ArangoError: AQL: edge attribute missing or invalid (while
executing) 16 minutes ago
[24213] Service "/myshop" encountered error 400 while handling POST
http://127.0.0.1:8529/_db/key2publish/myshop/mycustomendpoint 16 minutes ago
[24213] at Tree.dispatch (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:135:7)
27 minutes ago
[24213] at dispatch (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:426:3)
27 minutes ago
[24213] at next (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:410:7)
27 minutes ago
[24213] at next (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:414:15)
27 minutes ago
[24213] at Middleware.
(C:\ProgramData\ArangoDB-apps\_db\key2publish\myshop\APP\index.js:23:3)
27 minutes ago
[24213] at c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\node\node_modules\lodash\lodash.js:10052:25
27 minutes ago
[24213] at next (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:410:7)
27 minutes ago
[24213] at next (c:\Program Files\ArangoDB3
3.5.3\usr\share\arangodb3\js\server\modules\@arangodb\foxx\router\tree.js:412:15)

What is usually the source of such errors? Should I first look in
mycustomendpoint.js or in the LiveCode syntax or in the data or in a
different place?

Mark