ArgumentError in CollectionsController #update when updating and saving changes to logos

[elrayle]

Descriptive summary

Editing logos for a branded collection raises exception ArgumentError in Hyrax::Dashboard::CollectionsController#update

Rationale

Branding should be able to be updated without errors.

Expected behavior

When editing a collections that has a logo and add a second logo, saving should add the second logo.

Actual behavior

When editing a collections that has a logo and add a second logo, saving raises an exception.

Steps to reproduce the behavior

Prerequisite

Create a collection with a logo.

1. Navigate to: Dashboard -> Collections
2. Click button: New Collection
3. Select type: User Collection (definitely has branding enabled)
4. Set title: BRANDED COLLECTION (or other meaningful name)
5. Click tab: Branding
6. Click button for logo: Choose File
7. Select any file
8. Click button: Save

To reproduce:

1. Navigate to: Dashboard -> Collections
2. Select Action beside the collection created in prerequisites
3. Click tab: Branding
4. To add another logo, click button for logo: Choose File
5. Select any file
6. Click button: Save

This will raise the exception seen in the Actual behavior section.

Related work

Issue #5470