Previously, the `^` marker was misaligned if the line above contained tabs.
Fixes T7282.
Note: This commit handles a very subtle edge-case differently: When the passed
in column number is larger than the length of the line. Previously, the `^`
marker would be faithfully placed at that exact column number. Now, it is placed
at the end of the line instead (after the last character of the line to be
precise). Ideally, we should define what should happen in edge cases, but that's
out of scope for this PR.
f80463120b