Fixed amount calculations

src/models/entities/Donation.ts

@@ -1,10 +1,9 @@
-import { PrimaryGeneratedColumn, Column, ManyToOne, Entity, TableInheritance } from "typeorm";
 import {
   IsInt,
   IsNotEmpty,
-  IsOptional,
-  IsPositive,
+  IsOptional
 } from "class-validator";
+import { Entity, ManyToOne, PrimaryGeneratedColumn, TableInheritance } from "typeorm";
 import { Participant } from "./Participant";
 
 /**
@@ -32,5 +31,5 @@ export abstract class Donation {
    * The donation's amount in cents (or whatever your currency's smallest unit is.).
    * The exact implementation may differ for each type of donation.
    */
-  abstract amount: number;
+  abstract amount: number | Promise<number>;
 }