Democracy is more than just voting. The Pledge to Safeguard the Election (https://www.thepledge.site/pledge-to-safeguard-the-election) is a way for voters to make sure their vote COUNTS by digging into the grit of the electoral process and making sure that electoral officials follow the same rules that have been applied to previous modern elections.
If mail-in ballots are challenged, the results are closer than expected and Trump then begins to manipulate the electoral college or attempts to move the process to the House, we will indeed have a constitutional crisis. We need to cast our votes on the House and local levels with this in mind and then follow through AFTER the election to make sure the normal process is followed by keeping pressure on electoral officials of all kinds at all levels. A fuller explanation can be found in the article “Stop the Coming Election Crisis” (https://medium.com/illumination-curated/sign-the-pledge-to-safeguard-the-election-b4daae7efd93) and “Wake Up America! What if Trump Loses the Election and Really DOES Refuse to Go Peacefully?” (https://medium.com/illumination-curated/a-call-to-safeguard-the-election-3a81c9192071?source=friends_link&sk=364c7b349fff6447f2573c6370449846).