fix panic when closing day with <5 admissions

[zramsay]

this ugly hack

point-of-sale/main.go

Lines 504 to 510 in 7904668

	if err := db.QueryRow("SELECT date FROM visits WHERE invoice_id=5").Scan(&date); err != nil {
	if err := db.QueryRow("SELECT date FROM visits WHERE invoice_id=10").Scan(&date); err != nil {
	if err := db.QueryRow("SELECT date FROM visits WHERE invoice_id=15").Scan(&date); err != nil {
	panic(err)
	}
	}
	}