default values for /sim/model/c172p/lighting/particles/* are not set

[www2000]

He i have found a problem that there is no default values for /sim/model/c172p/lighting/particles
this generate an nasal runtime error (nil used in numeric context) in $AIRCRAFT/c172p/Nasal/particle-effects-manager.nas
I run next.

[wlbragg]

Thank for the report, I'll take a look.