Pass error class explicitly for clarity

Author: eregon

src/main/ruby/truffleruby/core/random.rb

@@ -67,7 +67,7 @@ def self.srand(seed = undefined)
   end
 
   def self.rand(limit = undefined)
-    Truffle::RandomOperations.random(Primitive.thread_randomizer, limit)
+    Truffle::RandomOperations.random(Primitive.thread_randomizer, limit, TypeError)
   end
 
   def self.urandom(size)
@@ -88,7 +88,7 @@ def initialize(seed = undefined)
   end
 
   def rand(limit = undefined)
-    Truffle::RandomOperations.random(@randomizer, limit)
+    Truffle::RandomOperations.random(@randomizer, limit, TypeError)
   end
 
   def seed

src/main/ruby/truffleruby/core/truffle/random_operations.rb

@@ -12,7 +12,7 @@ module Truffle
   module RandomOperations
 
     # MRI: rand_random
-    def self.random(randomizer, limit, error = TypeError)
+    def self.random(randomizer, limit, error)
       if Primitive.undefined?(limit)
         return randomizer.random_float
       end