In case there were no chapters to migrate the read or bookmark status, a request with an empty list was sent to the server.
This caused an exception on the server which resulted in a request failure which at the end caused the migration to fail
In case "skip duplicated chapters" is enabled and the next chapter is from a different scanlator, the initial opened chapter should still be used to remove duplicated chapters.
Otherwise, the original scanlator would get lost and the scanlator of the next chapter would get used, which was only a fallback chapter, because the initial chapters scanlator did not have a next chapter.
In case images are requested of a slow source, aborting image requests that are already in progress will cause the server to take forever for new source image requests because it's still processing the aborted image requests.
Thus, aborting ongoing image request might cause more harm than good, since the server will basically become "unresponsive" for new images requests of this source.
By only aborting pending requests, that have not been sent to the server yet, new image requests will only be handled once the active requests are done, preventing the server from getting spammed with image requests that potentially are just getting aborted immediately again (e.g. due to scrolling quickly in the source browse page), but still will be handled by the server, blocking new requests
In case a manga was completely downloaded, the grouped chapters did not contain a list for the specific manga id, resulting in an TypeError due to trying to use the array as if it was not undefined
Changed with 0c4ce2c9c5, but it does not work because the chapters state could have changed in the meantime, changing the chapters included in the query response, which is not represented by the cached query
There is a potential that the cached chapters state is outdated, but this is a marginal issue and is preferred over sending a request to the server everytime for data that is most likely already known.
The triggered downloads will also reflect what is currently shown in the UI, so it will most likely never be known if some chapter state was outdated.
In case the next 5 chapters should get downloaded and they are all the same chapter from different scanlators, then the download actually only included 1 chapter.
To fix this duplicated chapters are counted as 1 chapter
In case a manga was fully read and a new chapter was found during a library update, the resume button was not correctly updated and pointed to the first chapter.
This regression was introduced with fe2cb682b6
Instead of checking if download ahead is required because not enough unread downloaded chapters existed, it just downloaded the next n unread undownloaded chapters
