The "appliedMigrationId" was converted to it's index of the "METADATA_MIGRATIONS" and then was compared to the "migration id" which starts at 1 instead of 0
The wrong chapter list was used.
"chapters" is the filtered list of chapters, which e.g. doesn't contain duplicated chapters.
This caused the "chapter source order" to potentially be higher than the total chapters of the manga.
The end result of this was that the fetched state of the pages wasn't properly detected causing errors due to rendering the reader before it was in the correct state
Only really relevant for the "progress bar slot" prop to prevent the slots from unnecessary re-rendering, since depending on the total pages, this can impact the render performance on page changes heavily
The page change handling of the progress bar was inverted while RTL was the set readers reading direction.
However, this is only relevant for the horizontal progress bar
The default timeout of "notistack" is 5s by default, however, this makes it more clear and also prevents any behaviour changes in the future, in case the default timeout gets changed
When the end of the scrollable element is reached in the continuous reader, the last image is not visible anymore.
Thus, the "firstVisibleImageIndex" is invalid and gets incorrectly used for the "isEndReached" case which results in an TypeError when trying to use the actual page via the index
The thresholds are only for detecting if a specific side of the image is in the viewport.
For the check if the image fills the whole viewport, the thresholds incorrectly detect this depending on the readers reading direction.
E.g. in the continuous horizontal pager with theme direction LTR and reader reading direction RTL, the left threshold will be the total width of the viewport plus one which will lead to out of view images to be detected as completely filling the viewport
Both hardcoded thresholds (MIN_VISIBLE_PX 0 or 1) break the "first visible image" detection in different kind of ways.
With 1 it always incorrectly jumps to the next page when resuming a chapter, since the page to resume will bet at 0px.
With 0 it fails to detect the correct first visible image when scrolling (automatically not via wheel or touch) to another page.
This happens when there is no gap between the pages because in this case the start of the current image and the end of the previous image are at the same coordinate.
Thus, the previous image is still incorrectly detected as visible since the end still aligns with the viewports start/end
In case the "currentChapter" is undefined, it means that the state has not been set yet.
In case the "currentChapter" does not exist, it would be set to "null".
As explained in c70287363a8e9308fc294baf83c5656a21a479b1, the "chapterSourceOrder" does not start at 0, thus, in case it's the last known chapter, "doesChapterExist" was always false due to subtracting 1 of the total chapters
Instead of immediately updating the value once the page count changed, it got updated after "pagesToSpreadState" changed, which was after the rendering finished.
This was the actual root cause of what was tried to be fixed with 9ab6ec89c7
For the double pager the current page text needs more reserved space since two pages are displayed at once which changes the current page text to "<page1>-<page2>" instead of just "<page1>"
I was unable to find a fix for this problem, thus, the only solution I see is disabling this functionality for the continuous readers.
Due to preloading leading pages, the layout got shifted once the pages got loaded.
This messed with the scroll position which caused the top of the scrolled into views pages to not be at the top of the viewport anymore.
Sometimes the reader settings state took too long to get set and the previews were shown using the default settings first, since they are set as the default values of the reader settings context, and then again for the final settings
