separate this a bit

code/modules/projectiles/guns/energy.dm

@@ -206,6 +206,9 @@
 		var/initial_index = new_index
 		while(!IS_VALID_INDEX(new_index) && (new_index != initial_index))
 			new_index = INCREMENT_OR_WRAP(new_index)
+		if(initial_index == new_index)		//cycled through without finding another
+			new_index = current_index
+
 	set_firemode_index(new_index, user_for_feedback)
 
 /obj/item/gun/energy/proc/user_set_firemode_to_prev(mob/user_for_feedback)
@@ -216,6 +219,9 @@
 		var/initial_index = new_index
 		while(!IS_VALID_INDEX(new_index) && (new_index != initial_index))
 			new_index = DECREMENT_OR_WRAP(new_index)
+		if(initial_index == new_index)		//cycled through without finding another
+			new_index = current_index
+
 	set_firemode_index(new_index, user_for_feedback)
 #undef INCREMENT_OR_WRAP
 #undef DECREMENT_OR_WRAP

code/modules/projectiles/guns/energy/stun.dm

@@ -27,14 +27,14 @@
 	var/altfire_delay = 40
 
 /obj/item/gun/energy/e_gun/advtaser/altafterattack(atom/target, mob/user, proximity_flag, params)
+	. = TRUE
 	if(last_altfire > world.time + altfire_delay)
-		return FALSE
+		return
 	var/current_index = current_firemode_index
 	set_firemode_to_type(/obj/item/ammo_casing/energy/electrode)
 	process_afterattack(target, user, proximity_flag, params)
 	set_firemode_index(current_index)
 	last_altfire = world.time
-	return TRUE
 
 /obj/item/gun/energy/e_gun/advtaser/cyborg
 	name = "cyborg taser"