Commit 1c4f685b13 replaced
configuration-layer--layers (a list of cfgl-layer objects) with
configuration-layer--used-layers (a list of symbols). It also changed the
configuration-layer/insert-lazy-install-configuration function to use the
new variable, but it did not change the sort predicate. Consequently, the
function started failing:
Wrong type argument: listp, spacemacs-purpose
In addition, because sort is destructive, the function also deleted values
from configuration-layer--used-layers.
This commit fixes the sort predicate so that the function returns the
correct value, and it copies the list before sorting to avoid modifying
configuration-layer--used-layers.
* core/core-configuration-layer.el
(configuration-layer/insert-lazy-install-configuration): Use string<
as the sort predicate, and give sort a copy of the list.