Interaction with Microsoft's C# extension causes error spam

When a test fails and is added to the Problems tab with red squiggles below, this seems to confuse Microsoft's official C# extension. Whenever I hover over one of the test errors reported by this extension, the C# extension pops up with

[Error - 09:48:50] Request textDocument/codeAction failed.
Message: span
Code: -32000
[object Object]

This is probably really the fault of Microsoft's C# extension, but since it's such a widespread extension maybe it could still be worked around on your end. From the looks of it, I think it's trying to suggest a code action, but gets confused by the way this extension reports the test errors somehow - I do notice the red squiggles go from the start of the line, including indents.

Reproduce a failing test in VS Code with Microsoft's official C# extension enabled, then inspect how the test failure is reported in the Problems tab, especially the red-squiggle span. Compare hovering over these errors with the extension disabled; done means hovering no longer produces repeated textDocument/codeAction error messages.

Written by the indexing model from the issue text.