Simplify experienced logic and remove edge case of modifier not added

src/main/java/slimeknights/tconstruct/tools/modifiers/upgrades/general/ExperiencedModifier.java

@@ -75,7 +75,7 @@ private void onEntityKilled(LivingDeathEvent event) {
    */
   private void onExperienceDrop(LivingExperienceDropEvent event) {
     // if the entity was killed by one of our arrows, boost the experience from that
-    int experienced = event.getEntityLiving().getCapability(TinkerDataCapability.CAPABILITY).resolve().stream().mapToInt(data -> data.get(EXPERIENCED, -1)).sum();
+    int experienced = event.getEntityLiving().getCapability(TinkerDataCapability.CAPABILITY).resolve().map(data -> data.get(EXPERIENCED)).orElse(-1);
     if (experienced > 0) {
       event.setDroppedExperience(boost(event.getDroppedExperience(), experienced));
       // experienced being zero means it was our arrow but it was not modified, do not check the held item in that case