Better error in stats.

lib/memcached/memcached.rb

@@ -409,6 +409,10 @@ Please note that when pipelining is enabled, setter and deleter methods do not r
 
     Lib.memcached_stat_free(@struct, stat_struct)
     stats
+  rescue Memcached::SomeErrorsWereReported => _
+    e = _.class.new("Error getting stats")
+    e.set_backtrace(_.backtrace)
+    raise e
   end
 
   ### Operations helpers

test/unit/memcached_test.rb

@@ -746,6 +746,11 @@ class MemcachedTest < Test::Unit::TestCase
     assert_instance_of String, stats[:version].first
   end
 
+  def test_missing_stats
+    cache = Memcached.new('localhost:43041')
+    assert_raises(Memcached::SomeErrorsWereReported) { cache.stats }
+  end
+
   # Clone
 
   def test_clone