Do not raise an exception if the body is missing from the response (#1044)

Author: andrehjr

lib/vcr/structs.rb

@@ -31,7 +31,7 @@ def force_encode_string(string, encoding)
         end
 
         def try_encode_string(string, encoding_name)
-          return string if encoding_name.nil?
+          return string if encoding_name.nil? || string.nil?
 
           encoding = Encoding.find(encoding_name)
           return string if string.encoding == encoding

spec/lib/vcr/structs_spec.rb

@@ -149,6 +149,13 @@ def body_hash(key, value)
         expect(i.response).to eq(Response.new(ResponseStatus.new))
       end
 
+      it 'uses a blank body if it is missing from the response' do
+        hash['response']['body'] = { 'encoding' => 'US-ASCII' }
+
+        i = HTTPInteraction.from_hash(hash)
+        expect(i.response.body).to eq('')
+      end
+
       it 'decodes the base64 body string' do
         hash['request']['body'] = body_hash('base64_string', Base64.encode64('req body'))
         hash['response']['body'] = body_hash('base64_string', Base64.encode64('res body'))