I claim the ornamental design for an aisle barrier, as shown and described.
FIG. 1 is a front view of the preferred embodiment.
FIG. 2 is a top view of the preferred embodiment.
FIG. 3 is a left side view of the preferred embodiment, and the right side view is a mirror image thereof.
FIG. 4 is a front view of a first alternate embodiment.
FIG. 5 is a top view of the first alternate embodiment.
FIG. 6 is a left side view of the first alternate embodiment, and the right side view is a mirror image thereof.
FIG. 7 is a front view of a second alternate embodiment.
FIG. 8 is a top view of the second alternate embodiment; and,
FIG. 9 is a left side view of the second alternate embodiment, and the right side view is a mirror image thereof.
The cross-hatching is shown for illustrative purposes only and form no part of the claimed design. The rear views form no part of the design and are omitted.