I did find this information:
If a candidate dies before the general election but after they've secured their party's nomination, it's a relatively simple fix: The deceased candidate's party picks a replacement (who may or may not be the vice presidential candidate from the ticket), and that replacement is on the ballot on Election Day. Both the Republican and the Democratic parties have rules about how their parties would fill the vacancy.
If a candidate dies between the popular vote and the meeting of the Electoral College the parties follow the same process to fill the vacancy on the ticket. If the candidate that dies is on the winning ticket, it's still the party's responsibility to provide a new candidate their electors could vote into office.
But here, the political implications are more serious because it takes some of the power away from the people; they don't get to vote again. The replacement candidate's name goes on the Electoral College ballot only, and their political party expects its electors to vote the replacement candidate into office.
There's no federal law saying the electors have to vote for the new candidate. Theoretically, if the candidate to whom they pledged their votes dies and their party doesn't name a preferred successor, electors could vote for the party's VP candidate, a third-party candidate or a leading contender within their own party. But state laws vary on the matter.