Fix warnings

Author: route

lib/ferrum/page/screenshot.rb

@@ -38,7 +38,7 @@ def screenshot(**opts)
         save_file(path, bin)
       end
 
-    def pdf(**opts)
+      def pdf(**opts)
         path, encoding = common_options(**opts)
         options = pdf_options(**opts).merge(transferMode: "ReturnAsStream")
         handle = command("Page.printToPDF", **options).fetch("stream")

spec/browser_spec.rb

@@ -57,7 +57,7 @@ module Ferrum
       path = "#{PROJECT_ROOT}/spec/support/no_chrome"
 
       expect {
-        browser = Browser.new(browser_path: path)
+        Browser.new(browser_path: path)
       }.to raise_error(
         Ferrum::ProcessTimeoutError,
         "Browser did not produce websocket url within 2 seconds"

spec/support/server.rb

@@ -64,6 +64,7 @@ def initialize(app: nil, host: "127.0.0.1", port: nil)
       @host = host
       @port = port || find_available_port(host)
       @app = app || Application.new
+      @server_thread = nil
     end
 
     def base_url(path = nil)