Handle recursive array

clean up all warnings by using new Environment

lib/liquid/variable.rb

@@ -95,15 +95,21 @@ module Liquid
 
     def render_to_output_buffer(context, output)
       obj = render(context)
+      render_obj_to_output(obj, output)
+      output
+    end
 
-      if obj.is_a?(Array)
-        output << obj.join
-      elsif obj.nil?
-      else
+    def render_obj_to_output(obj, output)
+      case obj
+      when NilClass
+        # Do nothing
+      when Array
+        obj.each do |o|
+          render_obj_to_output(o, output)
+        end
+      when
         output << obj.to_s
       end
-
-      output
     end
 
     def disabled?(_context)

lib/liquid/version.rb

@@ -2,5 +2,5 @@
 # frozen_string_literal: true
 
 module Liquid
-  VERSION = "5.6.0.alpha"
+  VERSION = "5.6.0.rc1"
 end

test/integration/variable_test.rb

@@ -130,6 +130,10 @@ class VariableTest < Minitest::Test
     assert_template_result('bar', '{{ foo }}', { 'foo' => :bar })
   end
 
+  def test_nested_array
+    assert_template_result('', '{{ foo }}', { 'foo' => [[nil]] })
+  end
+
   def test_dynamic_find_var
     assert_template_result('bar', '{{ [key] }}', { 'key' => 'foo', 'foo' => 'bar' })
   end