Avoid deprecation warning when raising

When calling + or since between two time objects we should avoid
emitting two deprecation messages and avoiding any deprecation messages
if the deprecated fallback raises an exception.

activesupport/CHANGELOG.md

@@ -1,6 +1,6 @@
-*   Deprecate addition for `Time` instances with `ActiveSupport::TimeWithZone`.
+*   Deprecate addition and since between two `Time` and `ActiveSupport::TimeWithZone`.
 
-    Previously adding time instances together such as `10.days.ago + 10.days.ago` produced a nonsensical future date. This behavior is deprecated and will be removed in Rails 8.0.
+    Previously adding time instances together such as `10.days.ago + 10.days.ago` or `10.days.ago.since(10.days.ago)` produced a nonsensical future date. This behavior is deprecated and will be removed in Rails 8.1.
 
     *Nick Schwaderer*
 

activesupport/lib/active_support/core_ext/time/calculations.rb

@@ -218,11 +218,12 @@ class Time
   def since(seconds)
     self + seconds
   rescue TypeError
+    result = to_datetime.since(seconds)
     ActiveSupport.deprecator.warn(
       "Passing an instance of #{seconds.class} to #{self.class}#since is deprecated. This behavior will raise " \
       "a `TypeError` in Rails 8.1."
     )
-    to_datetime.since(seconds)
+    result
   end
   alias :in :since
 

activesupport/lib/active_support/time_with_zone.rb

@@ -303,11 +303,11 @@ module ActiveSupport
         begin
           result = utc + other
         rescue TypeError
+          result = utc.to_datetime.since(other)
           ActiveSupport.deprecator.warn(
             "Adding an instance of #{other.class} to an instance of #{self.class} is deprecated. This behavior will raise " \
             "a `TypeError` in Rails 8.1."
           )
-          result = utc.since(other)
           result.in_time_zone(time_zone)
         end
         result.in_time_zone(time_zone)

activesupport/test/core_ext/time_with_zone_test.rb

@@ -407,6 +407,15 @@ class TimeWithZoneTest < ActiveSupport::TestCase
     end
   end
 
+  def test_plus_with_invalid_argument
+    twz = ActiveSupport::TimeWithZone.new(Time.utc(2000, 1, 1), @time_zone)
+    assert_not_deprecated(ActiveSupport.deprecator) do
+      assert_raises TypeError do
+        twz + Object.new
+      end
+    end
+  end
+
   def test_plus_with_duration
     assert_equal Time.utc(2000, 1, 5, 19, 0, 0), (@twz + 5.days).time
   end