Provide a better error message if a user mistypes the name of script with runner

Add tests for detecting bad options for runner

railties/lib/rails/commands/runner.rb

@@ -58,5 +58,11 @@
   $0 = code_or_file
   Kernel.load code_or_file
 else
-  eval(code_or_file, binding, __FILE__, __LINE__)
+  begin
+    eval(code_or_file, binding, __FILE__, __LINE__) 
+  rescue SyntaxError,NameError => err
+    $stderr.puts "Please specify a valid ruby command or the path of a script to run."
+    $stderr.puts "Run '#{$0} -h' for help."
+    exit 1
+  end
 end

railties/test/application/runner_test.rb

@@ -74,6 +74,16 @@ def test_default_environment
       assert_match "development", Dir.chdir(app_path) { `bin/rails runner "puts Rails.env"` }
     end
 
+    def test_runner_detects_syntax_errors
+      Dir.chdir(app_path) { `bin/rails runner "puts 'hello world" 2>&1` }
+      refute $?.success? 
+    end
+
+    def test_runner_detects_bad_script_name
+      Dir.chdir(app_path) { `bin/rails runner "iuiqwiourowe" 2>&1` }
+      refute $?.success? 
+    end
+
     def test_environment_with_rails_env
       with_rails_env "production" do
         assert_match "production", Dir.chdir(app_path) { `bin/rails runner "puts Rails.env"` }