Fixed spelling

ref #193

src/models/actions/update/UpdateFixedDonation.ts

@@ -20,7 +20,7 @@ export class UpdateFixedDonation extends UpdateDonation {
      */
     public async update(donation: FixedDonation): Promise<FixedDonation> {
         donation.amount = this.amount;
-        donation.payedAmount = this.payedAmount;
+        donation.paidAmount = this.paidAmount;
         donation.donor = await this.getDonor();
 
         return donation;