Comment 2 for bug 1216859

style="stroke: red; stroke-width: 5;"
gets split to
["stroke: red", " stroke-width: 5"]
and then to
[["stroke", "red"], ["stroke-width", "5"]]
which is correct.

style="stroke: red; stroke-width: 5; "
gets split to
["stroke: red", " stroke-width: 5", " "]
and then to
[["stroke", "red"], ["stroke-width", "5"], [" "]]
which causes the error because the last element only has one element, two are expected.

I don't know if it is possible to create such a style attribute, but it is definitely possible to open a file with such style attributes and then try to export it triggering this error. The style attributes are not changed (at least until you change a style).