An insurer shall furnish, upon written request of any person claiming to have a loss under an insurance contract issued by the insurer, forms for proof of loss for completion by the person, but the insurer shall not, by reason of the requirement so to furnish forms, have any responsibility for or with reference to the completion of the proof or the manner of any completion or attempted completion. Failure or refusal to furnish the form upon written request or written notice of a loss shall constitute waiver of the right of the insurer to require proof of loss.