Fix crash on broken model

engine/client/gl_rlight.c

@@ -104,7 +104,7 @@ void R_MarkLights( dlight_t *light, int bit, mnode_t *node )
 	msurface_t	*surf;
 	int		i;
 	
-	if( node->contents < 0 )
+	if( !node || node->contents < 0 )
 		return;
 
 	dist = PlaneDiff( light->origin, node->plane );
@@ -487,4 +487,4 @@ colorVec R_LightPoint( const vec3_t p0 )
 	VectorSet( p1, p0[0], p0[1], p0[2] - 2048.0f );
 
 	return R_LightVec( p0, p1, NULL, NULL );
-}
+}