Prevent `RequestEncoder#encode_params` to parse falsey params

When a `get` method called with `as: :json` and `params: nil` or
`params: false` (explicitly or implicitly)
`RequestEncoder#encode_params` converts it into a `null` or `false`
value which includes a unexpected `null=` or `false` query string into
request URL. From now on `RequestEncoder#encode_params` checks whether
`params` is nil or not otherwise returns.

Move down `nil` conversion guard


Update CHANGELOG.md

1 files changed, 1 insertions, 1 deletions

diff --git a/actionpack/lib/action_dispatch/testing/request_encoder.rb b/actionpack/lib/action_dispatch/testing/request_encoder.rb
index 01246b7a2e..9889f61951 100644
--- a/actionpack/lib/action_dispatch/testing/request_encoder.rb
+++ b/actionpack/lib/action_dispatch/testing/request_encoder.rb
@@ -34,7 +34,7 @@ module ActionDispatch
     end
 
     def encode_params(params)
-      @param_encoder.call(params)
+      @param_encoder.call(params) if params
     end
 
     def self.parser(content_type)