Ignore error if nested cause is ignored

Traverse the error causes tree to see if any nested error cause is
ignored.

lib/appsignal/rack/body_wrapper.rb

@@ -81,8 +81,9 @@ def appsignal_report_error(error)
 
       def appsignal_accepted_error?(error)
         return true unless error.cause
+        return false if IGNORED_ERRORS.include?(error.cause.class)
 
-        !IGNORED_ERRORS.include?(error.cause.class)
+        appsignal_accepted_error?(error.cause)
       end
     end
 

spec/lib/appsignal/rack/body_wrapper_spec.rb

@@ -103,6 +103,19 @@
       expect(transaction).to_not have_error
     end
 
+    it "does not report EPIPE error when it's the nested error cause" do
+      error = error_with_nested_cause(StandardError, "error message", Errno::EPIPE)
+      fake_body = double
+      expect(fake_body).to receive(:each).once.and_raise(error)
+
+      wrapped = described_class.wrap(fake_body, transaction)
+      expect do
+        expect { |b| wrapped.each(&b) }.to yield_control
+      end.to raise_error(StandardError, "error message")
+
+      expect(transaction).to_not have_error
+    end
+
     it "closes the body and tracks an instrumentation event when it gets closed" do
       fake_body = double(:close => nil)
       expect(fake_body).to receive(:each).once.and_yield("a").and_yield("b").and_yield("c")
@@ -444,4 +457,18 @@ def error_with_cause(klass, message, cause)
   rescue => error
     error
   end
+
+  def error_with_nested_cause(klass, message, cause)
+    begin
+      begin
+        raise cause
+      rescue
+        raise klass, message
+      end
+    rescue
+      raise klass, message
+    end
+  rescue => error
+    error
+  end
 end