recover gracefully when admin views deleted project

[davidsbailey]

Background

https://app.honeybadger.io/projects/3240/faults/44663286 indicates that admins are getting 500 when following urls to deleted projects. This is because the admin panel displays content moderation info

code-dot-org/dashboard/app/views/levels/_admin.html.haml

Lines 88 to 90 in f9bf7c8

	- storage_apps = StorageApps.new(storage_id('user'))
	- content_moderation_disabled = storage_apps.content_moderation_disabled?(params[:channel_id])
	%li

and the content moderation logic raises if you check whether a deleted project requires moderation:

code-dot-org/shared/middleware/helpers/storage_apps.rb

Lines 209 to 213 in a23e3ca

	def content_moderation_disabled?(channel_id)
	_owner, storage_app_id = storage_decrypt_channel_id(channel_id)
	row = @table.where(id: storage_app_id).exclude(state: 'deleted').first
	raise NotFound, "channel `#{channel_id}` not found" unless row

Description

The solution is to not raise for deleted projects. In the admin panel this suppresses any errors long enough for the page to redirect. This is also harmless for non-admins in production, since an earlier lookup to the project would 404 prior to any 404 being generated by the line modified in this PR:

code-dot-org/shared/middleware/files_api.rb

Line 875 in 6269b4b

project_type = storage_apps.project_type_from_channel_id(encrypted_channel_id)

Testing

Manually verified that when an admin views a deleted project, they now get redirected to their latest project of that type instead of seeing a 500 error.

[islemaster]

Thanks for this fix Dave! Looks great, very clear reasoning on the solution.