Happens all the time; usually it's diesels getting gas accidentally but sometimes it's a gasser getting diesel. No harm, just get good gas and dry the plugs and good to go.
4 years ago my boss put 15 gallons of gas in an 07 Duramax (26 gallon tank) and drove it 50 miles and it started running bad and the exhaust smelled funny. Had me drive it 5 more miles to the shop where they found out about the gas. Cost $500 to have it drained and flushed out and as far as I know it's still running fine today with nothing failed or replaced. Nobody can explain why.