`Download All` button is enabled when there's no attachments

[emenslin]

Describe the bug
On a record with no attachments, if you open the attachment gallery, the download all button is enabled, in 7.11.4 the button was disabled.

To Reproduce
Steps to reproduce the behavior:

1. Create a new record on any table that supports attachments
2. Save without adding an attachment
3. Click the attachment icon in the top right
4. See error

Expected behavior
The button should be disabled to match the behavior in 7.11.4

Screenshots
7.12:

7.11.4:

Please fill out the following information manually:

• OS: Windows 11
• Browser: Chrome
• Specify 7 Version: 7.12
• Database Name: ojsmnh
• Collection name: fossil invertebrates
• User Name: spadmin
• URL: https://ojsmnh20260326-v7120-prerelease.test.specifysystems.org/specify/