Display more specific error when snippet cannot be found

lib/liquid/tags/render.rb

@@ -55,6 +55,9 @@ module Liquid
       elsif @template_name_expr.is_a?(String)
         partial = PartialCache.load(template, context: context, parse_context: parse_context)
         template_name = partial.name
+      elsif template.nil?
+        template_name = @template_name_expr.respond_to?(:name) ? @template_name_expr.name : @template_name_expr
+        raise FileSystemError, "No such template '#{template_name}'"
       else
         raise ::ArgumentError, parse_context.locale.t("errors.argument.render")
       end

test/integration/tags/snippet_test.rb

@@ -480,6 +480,25 @@ class SnippetTest < Minitest::Test
 
       assert_match("Expected end_of_string but found id", exception.message)
     end
+
+    def test_render_with_non_existent_tag
+      template = Liquid::Template.parse(<<~LIQUID.chomp, line_numbers: true)
+        {% snippet foo %}
+        {% render non_existent %}
+        {% endsnippet %}
+
+        {% render foo %}
+      LIQUID
+
+      expected = <<~TEXT
+
+
+
+        Liquid error (foo line 2): No such template 'non_existent'
+      TEXT
+
+      assert_equal(expected, template.render('errors' => ErrorDrop.new))
+    end
   end
 
   class RigidMode < SnippetTest
@@ -956,6 +975,25 @@ class SnippetTest < Minitest::Test
       assert_match("Expected a string or identifier, found 123", exception.message)
     end
 
+    def test_render_with_non_existent_tag
+      template = Liquid::Template.parse(<<~LIQUID.chomp, line_numbers: true, error_mode: :rigid)
+        {% snippet foo %}
+        {% render non_existent %}
+        {% endsnippet %}
+
+        {% render foo %}
+      LIQUID
+
+      expected = <<~TEXT
+
+
+
+        Liquid error (foo line 2): No such template 'non_existent'
+      TEXT
+
+      assert_equal(expected, template.render('errors' => ErrorDrop.new))
+    end
+
     def test_render_with_no_identifier
       template = "{% render %}"