If people use bundle-collapser, the string 'insert-css' is replaced with a number.

Since bundle-collapser is run in the label phase and css-extract is run afterwards the debug phase, no css is extracted -- no insert-css strings exist in the code after bundle-collapser runs.

Since we rely on module names being strings and since bundle-collapser is such a common plugin to use (IMO), I think running before the label phase is reasonable.

Is there a separate line of reasoning for the debug phase being chosen?