SPRK(ETRD): Check life value of destination before conducting

This prevents ETRD conducting to neighbours which are still in the
cooldown period after the previous spark. This is for consistency with
all other conduction rules, and to prevent behaviour being dependent
on particle order.

src/simulation/elements/SPRK.cpp

@@ -335,7 +335,7 @@ int Element_SPRK::update(UPDATE_FUNC_ARGS)
 					if (parts[r>>8].temp+10.0f<673.0f&&!sim->legacy_enable&&(receiver==PT_METL||receiver==PT_BMTL||receiver==PT_BRMT||receiver==PT_PSCN||receiver==PT_NSCN||receiver==PT_ETRD||receiver==PT_NBLE||receiver==PT_IRON))
 						parts[r>>8].temp = parts[r>>8].temp+10.0f;
 				}
-				else if (sender==PT_ETRD && parts[i].life==5) //ETRD is odd and conducts to others only at life 5, this could probably be somewhere else
+				else if (!parts[r>>8].life && sender==PT_ETRD && parts[i].life==5) //ETRD is odd and conducts to others only at life 5, this could probably be somewhere else
 				{
 					sim->part_change_type(i,x,y,sender);
 					parts[i].ctype = PT_NONE;