Something about runtime errors.

code/game/objects/effects/proximity.dm

@@ -109,4 +109,4 @@
 
 /obj/effect/abstract/proximity_checker/Crossed(atom/movable/AM)
 	set waitfor = FALSE
-	monitor.hasprox_receiver.HasProximity(AM)
+	monitor?.hasprox_receiver.HasProximity(AM)

code/modules/mob/living/simple_animal/parrot.dm

@@ -332,8 +332,8 @@
 		speak_chance *= 1.27 // 20 crackers to go from 1% to 100%
 		speech_shuffle_rate += 10
 		to_chat(user, "<span class='notice'>[src] eagerly devours the cracker.</span>")
-	..()
-	return
+		return // the cracker was deleted
+	return ..()
 
 //Bullets
 /mob/living/simple_animal/parrot/bullet_act(obj/item/projectile/Proj)

code/modules/power/singularity/particle_accelerator/particle.dm

@@ -59,7 +59,12 @@
 
 /obj/effect/accelerated_particle/proc/move()
 	if(!step(src,dir))
-		forceMove(get_step(src,dir))
+		var/turf/T = get_step(src,dir)
+		if(T)
+			forceMove(T)
+		else
+			qdel(src)
+			return
 	movement_range--
 	if(movement_range == 0)
 		qdel(src)

modular_citadel/code/modules/reagents/chemistry/recipes/fermi.dm

@@ -10,7 +10,7 @@
 	if(clear_conversion == REACTION_CLEAR_IMPURE | REACTION_CLEAR_INVERSE)
 		for(var/id in results)
 			var/datum/reagent/R = my_atom.reagents.has_reagent(id)
-			if(R.purity == 1)
+			if(!R || R.purity == 1)
 				continue
 
 			var/cached_volume = R.volume
@@ -25,7 +25,6 @@
 				my_atom.reagents.add_reagent(R.impure_chem, impureVol, FALSE, other_purity = 1)
 				R.cached_purity = R.purity
 				R.purity = 1
-	return
 
 //Called when temperature is above a certain threshold, or if purity is too low.
 /datum/chemical_reaction/proc/FermiExplode(datum/reagents/R0, var/atom/my_atom, volume, temp, pH, Exploding = FALSE)