[BUG] Deleted items in playlist break IIIF manifest generation

[cjcolvar]

Actual Behavior
When the underlying item of a playlist item gets deleted it breaks IIIF manifest generation.

Expected Behavior
Playlist items with deleted source content should appear in IIIF manifest with a displayable note for the user.

Steps to reproduce
Go to https://avalon-dev.dlib.indiana.edu/playlists/32/manifest.json

This is the error I'm seeing in the browser. My guess is that using the safe navigator could possibly resolve the error.

NoMethodError in PlaylistsController#manifest
undefined method `derivative_ids' for nil:NilClass
Extracted source (around line #29):

  def file_set_presenters
    # Only return master files that have derivatives to avoid oddities in the manifest and failures in iiif_manifest
    items.select { |item| item.master_file.derivative_ids.size.positive? }
  end

Done Looks Like

• if an item is added to a playlist and then deleted from Avalon, the playlist manifest will still generate without an error
• the playlist manifest should have a placeholderCanvas with message about the item being inaccessible
• in Avalon, the playlist item should display in the list of playlist items with a lock icon
• in Avalon, the playlist item should display a message about item being inaccessible in the media player when it is clicked on (or reached through auto-play)

[elynema]

working in IIIF; Ramp is displaying a different error message than we would expect to see. Re-test this in Ramp after Ramp samvera-labs/ramp#263 is merged.

[elynema]

@charumitraravi I see that #263 is not merged yet, so we'll actually need to wait on QA for this.

[elynema]

@charumitraravi #263 is now merged, this should be ready for QA

[charumitraravi]

@elynema
QA completed
This is the error I am getting in https://avalon-dev.dlib.indiana.edu/playlists/5

Steps:
1.I added a section from the item to this playlist.This got added as the 49th item.
2.I deleted the section which I added to the playlist
3.Tried to autoplay from the 48th item through 49th. Initially got the screen where it is supposed to show the item is no longer there, and then it displayed the error mentioned in the screenshot.

Note:This happens only when the deleted item is the last item in the playlist.
Similar behavior is observed in https://avalon-dev.dlib.indiana.edu/playlists/38 - The 18th item and 21st items are deleted here. The 18th item shows the status as expected.But after trying to autoplay the last item, the above error is displayed

[elynema]

@charumitraravi Can you create a new bug in the Ramp repository for this? The manifest looks ok, so this is an issue with how the deleted item is being loaded into the Ramp, in particularly the markers, when it's hit with autoplay.

[charumitraravi]

@elynema Added the bug