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r2610 | helixhorned | 2012-04-14 06:04:31 -0700 (Sat, 14 Apr 2012) | 5 lines

Fix a null pointer access in Polymer mouse picking.

Specifically, it was in the "determine searchwall when aiming at floor or
ceiling" part.  Now, if prsectors[]->ceil.plane (or ->floor.plane) is NULL,
we set the searchwall to the sector's firstwall and return.
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