Bukkit

This is what I get when using the example formula, but also on for example:

function levelReq(level) {
  var exp = 100 * level;
  return exp;
}

Killing one cow turns me to level 31000 and errors:

14:48:22 [WARNING] Task of 'LegacyEXP' generated an exception
java.lang.ClassCastException: java.lang.Double cannot be cast to java.lang.Integer
        at ryantakker.legacyexp.formula.JavascriptFormula.getReqEXP(JavascriptFormula.java:26)
        at ryantakker.legacyexp.formula.Formula.populateLevelMap(Formula.java:25)
        at ryantakker.legacyexp.formula.Formula.eval(Formula.java:36)
        at ryantakker.legacyexp.main.ExpPlugin.makeEquiv(ExpPlugin.java:249)
        at ryantakker.legacyexp.main.ExpPlugin$2.run(ExpPlugin.java:242)
        at org.bukkit.craftbukkit.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:126)
        at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:510)
        at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:212)
        at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:474)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:406)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)