NoMethodError: undefined method `unparsed_value' for #<Mail::OptionalField:0x007fbc2ad7b318>

[mountriv99]

Hi I think this is related to issue #99

OP was using "personalizations" and I'm using "custom_args" (works if i remove custom_args)

Still having this error in Rails 5

Rails 5.1.6
ruby 2.3.1p112
sendgrid-actionmailer-3.2.0

	def sendgrid_test(to_email)
		mail(:to => to_email, :subject => "Test", custom_args: {campaign: 'welcome'}) do |format|
			format.text { render :plain => "Test message" }
		end
	end

irb(main):027:0> ApplicationMailer.sendgrid_test("xxx@xxx.com").deliver_now
  Rendering text template
  Rendered text template (0.1ms)
ApplicationMailer#sendgrid_test: processed outbound mail in 22.7ms
Sent mail to xxx@xxx.com (8.9ms)
Date: Wed, 16 Feb 2022 18:45:23 +0800
From: XXX <no-reply@xxx.com>
To: xxx@xxx.com
Message-ID: <620cd5c3142c2_e78c3fde1243193c94884@MacBook-Air-2.local.mail>
Subject: Test
Mime-Version: 1.0
Content-Type: text/plain;
 charset=UTF-8
Content-Transfer-Encoding: 7bit
custom-args: {:campaign=>"welcome"}
X-SMTPAPI: {"category":"dev","filters":{"clicktrack":{"settings":{"enable":0}}}}

Test message
NoMethodError: undefined method 'unparsed_value' for #<Mail::OptionalField:0x007fbc2ad7b318>
	from (irb):27

[mountriv99]

Update: works if i downgrade to 3.1.1

I suspect it's caused by this commit
271de1c