Question: If the nominee dies after the policyholder but before the insurer pays, who gets the proceeds?
Answer: The nominee’s heirs or legal representatives, or the holder of a succession certificate, as the case may be.

Supporting evidence:
title: noc.irdai.gov.in/Insurance%20Act,1938%20-%20incorporating%20all%20amendments%20till%2020212021-08-12.pdf
quote: where the nominee, or if there are more nominees than one, a nominee or nominees, to whom sub-section ( 7 ) applies, die after the person whose life is insured but before the amount secured by the policy is paid, the amount secured by the policy, or so much of the amount secured by the policy as represents the share of the nominee or nominees so dying (as the case may be), shall be payable to the heirs or legal representatives of the nominee or nominees or the holder of a succession certificate, as the case may be
context: he policy shall be payable to such survivor or survivors.

ASSGNMENT OR TRANSFER OF POLICIES AND NOMINATIONS

(7) Subject to the other provisions of this section, where the holder of a policy of insurance on his own life nominates his parents, or his spouse, or his children, or his spouse and children, or any of them, the nominee or nominees shall be beneficially entitled to the amount payable by the insurer to him or them under sub-section ( 6 ) unless it is proved that the holder of the policy, having regard to the nature of his title to the policy, could not have conferred any such beneficial title on the nominee.
(8) Subject as aforesaid, where the nominee, or if there are more nominees than one, a nominee or nominees, to whom sub-section ( 7 ) applies, die after the person whose life is insured but before the amount secured by the policy is paid, the amount secured by the policy, or so much of the amount secured by the policy as represents the share of the nominee or nominees so dying (as the case may be), shall be payable to the heirs or legal representatives of the nominee or nominees or the holder of a succession certificate, as the case may be, and they shall be beneficially entitled to such amount.
(9) Nothing in sub-sections ( 7 ) and ( 8 ) shall operate to destroy or impede the right of any creditor to be paid out of the proceeds of any policy of life insurance.
(10) The provisions of sub-sections ( 7 ) and ( 8 ) shall apply to all policies of life insurance maturing for payment after the commencement of the Insurance Laws (Amendment) Act, 2015 (5 of 2015).
(11) Where a policyholder dies after the maturity of the policy but the proceeds and benefit of his policy has not been made to him because of his death, in such a case, his nominee shall be entitled to the proceeds and benefit of his policy.
(12) The provisions of this section shall not apply to any policy of life insurance to which section 6 of the Married Women's Property Act, 1874 (3 of 1874), applies or has at any time applied:

ASSGNMENT OR TRANSFER OF POLICIES AND NOMINATIONS

Provided that where a nomination made whether before or after the commencement of the Insurance Laws (Amendment) Act, 2015 (5 of 2015), in favour of the wife of the person who has insured his life or of his wife and children or any of them is expressed, whether or not on the face of the policy, as being made under this section, the said section 6 shall be deemed not to apply or not to have applied to the policy.