Updated relationships to be nullable

ref #11 #13

src/models/RunnerCard.ts

@@ -26,7 +26,7 @@ export class RunnerCard {
    * The runner that is currently associated with this card.
    */
   @IsOptional()
-  @ManyToOne(() => Runner, runner => runner.cards)
+  @ManyToOne(() => Runner, runner => runner.cards, { nullable: true })
   runner: Runner;
 
   /**
@@ -51,6 +51,6 @@ export class RunnerCard {
   /**
    * Used to link cards to a track scans.
    */
-  @OneToMany(() => TrackScan, scan => scan.track)
+  @OneToMany(() => TrackScan, scan => scan.track, { nullable: true })
   scans: TrackScan[];
 }