Program: 36630
Project: 36630
Buggy source:
public static String addPerk(String perkSlug,PlayerData player){
  String toReturn="String_Node_Str";
  Perk perk=PerkStore.getPerk(perkSlug);
  if (perk == null) {
    return "String_Node_Str";
  }
  ArrayList<Requirement> requirements;
  if (perk.getRequirements() != null) {
    requirements=perk.getRequirements();
  }
 else {
    requirements=new ArrayList<Requirement>();
  }
  boolean cont=true;
  for (  Requirement req : requirements) {
switch (req.action) {
case DONT:
      if (player.getPerkList().contains(req.getNameAsSlug())) {
        cont=false;
        toReturn="String_Node_Str" + req.name + "String_Node_Str";
      }
    break;
case HAVE:
  if (!player.getPerkList().contains(req.getNameAsSlug())) {
    cont=false;
    toReturn="String_Node_Str" + req.name + "String_Node_Str";
  }
break;
case LEVEL_EQUALS:
if (!(player.getSkillExp().get(req.name) == Integer.parseInt(req.extraData))) {
cont=false;
toReturn="String_Node_Str" + req.name + "String_Node_Str"+ req.extraData;
}
break;
case LEVEL_GREATER:
if (player.getSkillExp().get(req.name) < Integer.parseInt(req.extraData)) {
cont=false;
toReturn="String_Node_Str" + req.name + "String_Node_Str"+ req.extraData;
}
break;
case LEVEL_LESS:
if (player.getSkillExp().get(req.name) > Integer.parseInt(req.extraData)) {
cont=false;
toReturn="String_Node_Str" + req.name + "String_Node_Str"+ req.extraData;
}
break;
default :
cont=false;
break;
}
if (!cont) {
break;
}
}
if (cont && !player.getPerkList().contains(perkSlug)) {
addPerk(perk,player);
toReturn="String_Node_Str";
}
return toReturn;
}

Fixed version (ground truth):
public static String addPerk(String perkSlug,PlayerData player){
  String toReturn="String_Node_Str";
  Perk perk=PerkStore.getPerk(perkSlug);
  if (perk == null) {
    return "String_Node_Str";
  }
  ArrayList<Requirement> requirements;
  if (perk.getRequirements() != null) {
    requirements=perk.getRequirements();
  }
 else {
    requirements=new ArrayList<Requirement>();
  }
  boolean cont=true;
  for (  Requirement req : requirements) {
switch (req.action) {
case DONT:
      if (player.getPerkList().contains(req.getNameAsSlug())) {
        cont=false;
        toReturn="String_Node_Str" + req.name + "String_Node_Str";
      }
    break;
case HAVE:
  if (!player.getPerkList().contains(req.getNameAsSlug())) {
    cont=false;
    toReturn="String_Node_Str" + req.name + "String_Node_Str";
  }
break;
case LEVEL_EQUALS:
if (!(player.getSkillLevel(SkillHandler.getSkill(req.name)) == Integer.parseInt(req.extraData))) {
cont=false;
toReturn="String_Node_Str" + req.name + "String_Node_Str"+ req.extraData;
}
break;
case LEVEL_GREATER:
if (player.getSkillLevel(SkillHandler.getSkill(req.name)) < Integer.parseInt(req.extraData)) {
cont=false;
toReturn="String_Node_Str" + req.name + "String_Node_Str"+ req.extraData;
}
break;
case LEVEL_LESS:
if (player.getSkillLevel(SkillHandler.getSkill(req.name)) > Integer.parseInt(req.extraData)) {
cont=false;
toReturn="String_Node_Str" + req.name + "String_Node_Str"+ req.extraData;
}
break;
default :
cont=false;
break;
}
if (!cont) {
break;
}
}
if (cont && !player.getPerkList().contains(perkSlug)) {
addPerk(perk,player);
toReturn="String_Node_Str";
}
return toReturn;
}