Can. 927 It is absolutely wrong, even in urgent and extreme necessity, to consecrate one element without the other, or even to consecrate both outside the eucharistic celebration.
The Holy Eucharist can still be validly consecrated if both species are not present, but this is always gravely wrong. The Bread is transubstantiated the moment that it is consecrated, even before the wine is transubstantiated. If a priest were to die between the two, then the first is still validly consecrated.
The General Instruction of the Roman Missal:
324: “If the priest notices after the consecration or as he receives communion that water instead of wine was poured into the chalice, he pours the water into another container, then pours wine with water into the chalice and consecrates it. He says only part of the institution narrative related to the consecration of the chalice, without being obliged to consecrate bread again.”