[Fix rubocop#1200] Make Rails/TimeZone aware of safe navigation

`parse` raises on `nil` so autocorrect is not possible in this case.

changelog/fix_make_rails_time_zone_aware_of_safe_navigation.md

@@ -0,0 +1 @@
+* [#1200](https://github.com/rubocop/rubocop-rails/issues/1200): Make `Rails/TimeZone` aware of safe navigation. ([@earlopain][])

lib/rubocop/cop/rails/time_zone.rb

@@ -69,9 +69,10 @@ def on_send(node)
           return if !node.receiver&.str_type? || !node.method?(:to_time)
 
           add_offense(node.loc.selector, message: MSG_STRING_TO_TIME) do |corrector|
-            corrector.replace(node, "Time.zone.parse(#{node.receiver.source})")
+            corrector.replace(node, "Time.zone.parse(#{node.receiver.source})") unless node.csend_type?
           end
         end
+        alias on_csend on_send
 
         private
 

spec/rubocop/cop/rails/time_zone_spec.rb

@@ -135,6 +135,15 @@
       RUBY
     end
 
+    it 'registers an offense for `to_time` with safe navigation' do
+      expect_offense(<<~RUBY)
+        "2012-03-02 16:05:37"&.to_time
+                               ^^^^^^^ Do not use `String#to_time` without zone. Use `Time.zone.parse` instead.
+      RUBY
+
+      expect_no_corrections
+    end
+
     it 'does not register an offense for `to_time` without receiver' do
       expect_no_offenses(<<~RUBY)
         to_time