Error message about missing _id when updating an object.

[obrenckle]

Describe the bug
An error message is written to the console when adding a mod to an attached weapon attachment.
The mod is still created and nothing seems wrong with it.

To Reproduce
Steps to reproduce the behavior:

1. Go to an imported weapon (e.g. Heavy Blaster Pistol)
2. Open Item Attachment
3. Go to Add Mod tab
4. Add a new mod
5. Check Console

Expected behavior
No error message

Error message

Uncaught (in promise) Error: You must provide an _id for every object in the update data Array.
    activateListeners /starwarsffg/modules/items/item-sheet-ffg.js:786

modules/items/item-sheet-ffg.js:786

await this.object.update(
{
  system: {
    [itemType]: this.object.system[itemType],
  }
}

Desktop (please complete the following information):

• Foundry Version: [e.g. v12.331
• System Version: 1.903
• Hosted on Forge: No