Did the court of appeals violate the federalism principle of Erie R. Co. v. Tompkins, 304 U.S. 64 (1938) when it refused to apply Louisiana's substantive law of res-judicata

QUESTION(S) PRESENTED Did the court of appeals violate the federalism principle of Erie R. Co. v. Tompkins, 304 U.S. 64 (1938) when it refused to apply Louisiana’s substantive law of res judicata which would have allowed petitioner’s suit against his insurer for misrepresentation to proceed, causing a substantial variation in outcomes between State and federal litigation, influencing the choice of forum for future litigants in Louisiana seeking to hold their insurers responsible and depriving petitioner of his day in court he would otherwise enjoy in State court?