fix: Return nil for unparseable date fields instead of raising on read

Date accessors called Time.parse on whatever the API sent, so an epoch
integer raised TypeError and an empty or malformed string raised
ArgumentError at attribute read time, far from the request that produced
the value.

Parse only strings and return nil when the string is not a date, matching
the nil an absent date already reads as.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SQW83gyXeUG61RDrHEky97

Author: claude

lib/seam/base_resource.rb

@@ -103,17 +103,19 @@ def self.attribute_aliases
       def self.date_accessor(*attrs)
         attrs.each do |attr|
           define_method(attr) do
-            value = instance_variable_get(:"@#{attr}")
-
-            value.nil? ? nil : parse_datetime(value)
+            parse_datetime(instance_variable_get(:"@#{attr}"))
           end
         end
       end
 
       protected
 
       def parse_datetime(value)
+        return nil unless value.is_a?(String)
+
         Time.parse(value)
+      rescue ArgumentError
+        nil
       end
 
       def process_data_attributes(data)

spec/resources/base_resource_spec.rb

@@ -14,6 +14,22 @@
     it "parses a date string" do
       expect(device.created_at).to be_a(Time)
     end
+
+    it "returns nil for a missing date" do
+      expect(Seam::Resources::Device.new(device_id: "device_id_1234").created_at).to be_nil
+    end
+
+    it "returns nil for an empty string" do
+      expect(Seam::Resources::Device.new(created_at: "").created_at).to be_nil
+    end
+
+    it "returns nil for a string that is not a date" do
+      expect(Seam::Resources::Device.new(created_at: "not a date").created_at).to be_nil
+    end
+
+    it "returns nil for an epoch integer" do
+      expect(Seam::Resources::Device.new(created_at: 1_654_641_254).created_at).to be_nil
+    end
   end
 
   describe ".load_from_response" do