Added address check for donors that want a receipt

ref #65

src/errors/DonorErrors.ts

@@ -22,4 +22,15 @@ export class DonorIdsNotMatchingError extends NotAcceptableError {
 
 	@IsString()
 	message = "The ids don't match! \n And if you wanted to change a donor's id: This isn't allowed!"
+}
+
+/**
+ * Error to throw when a donor needs a receipt, but no address is associated with them.
+ */
+export class DonorReceiptAddressNeededError extends NotAcceptableError {
+	@IsString()
+	name = "DonorReceiptAddressNeededError"
+
+	@IsString()
+	message = "An address is needed to create a receipt for a donor. \n You didn't provide one."
 }