Firefox extension - vertical scrollbar - missing markers for highlights

[waluwaz]

Describe the bug
Bug: Some highlights do not generate a marker on the vertical scrollbar. Note that when those "ghost" highlights are exported out of Raindrop, the resulting csv has no value for the color column. Note that those highlights where orifinally created in Raindrop from an import file that didn't specify a colour (created by Diigo).
Context:
When a page has been bookmarked, the rendering of the page is modified to show highlighted text with some background colour. Also, the vertical scrollbar is modified to guide the users to the parts of the page that have been highlighted. The marks on the vertical scrollbar have the colour of the highlight (e.g. yellow or red).

To Reproduce
Steps to reproduce the behavior:

1. Import bookmarks in Raindrop. (In my case from Diigo. Note that the file from Diigo doesn't contain colours for the highlights, even though Diigo has several colours for highlights.).
2. Visit the page with the Firefox Browser Extension for Raindrop active (and no Diigo extension).
3. Notice that the highlighted text gets some highlighting. Good.
4. Notice that the vertical scrollbar has nothing to show where the highlighted parts are located. Not great.
5. Add a yellow highlight with Raindrop.
6. Notice after a split second that the vertical scrollbar of the browser shows the relative position of the highlights. Good.
7. Repeat with a red highlight. Good.

Expected behavior
All highlights should be illustrated/positioned on the vertical scrollbar. Whether they were imported or newly created. The marks on the scrollbar should be made yellow (which is the default in Raindrop, and the default in Diigo. But noone knows what the real colour was in Diigo.), or black for instance (as a sign that we don't know the actual colour).

Screenshots

The screenshot shows 3 highlights. The top one is old and imported. The next 2 are new and created in Raindrop. The vertical bar shows marks for the 2 new ones. Not for the old imported one, which is not so good.

Desktop (please complete the following information):

• OS: Ubuntu 24.04.3
• Browser Firefox 148.0
• Extension Raindrop 6.6.91

Additional context
Note that when the highlight is exported from Raindrop, the csv has no value for the old/imported highlight.

This is probably the reason for the issue. When Raindrop modifies the page, to show the text with some background, it uses a yellow colour (which is different from the usual Raindrop colour) for those highlights that don't have an explicit colour. But Raindrop seems to miss the same magic for the vertical scrollbar.

UPDATE: I realize the screenshot was taken when the Diigo extension was active. But the behaviour was the same before enabling the Diigo extension. (NB: At that time, Diigo was possibly still down/broken anyway.)