Fix yield_chunks method and improve error handling

Author: kojix2

lib/remote_input/downloader.rb

@@ -213,11 +213,12 @@ def download(output_path, &block)
       end
     end
 
-    private def yield_chunks(path)
-      path.open("rb") do |output|
+    private def yield_chunks(path, &block)
+      return unless block_given?
+      
+      path.open("rb") do |input|
         chunk_size = 1024 * 1024
-        chunk = +""
-        while output.read(chunk_size, chunk)
+        while chunk = input.read(chunk_size)
           yield(chunk)
         end
       end

test/test-downloader.rb

@@ -77,6 +77,21 @@ def teardown
       downloader.download(output_path)
       assert_equal("cached content", output_path.read)
     end
+
+    test("yield chunks when using cache") do
+      output_path = @tmp_dir + "cached_file"
+      content = "chunk1chunk2chunk3"
+      output_path.write(content)
+      
+      downloader = RemoteInput::Downloader.new("https://example.com/file")
+      
+      chunks = []
+      downloader.download(output_path) do |chunk|
+        chunks << chunk
+      end
+      
+      assert_equal(content, chunks.join)
+    end
   end
 
   sub_test_case("fallback URLs") do