first working pdf generation from class 🎉

ref #5

src/models/RunnerGroup.ts

@@ -1,15 +1,15 @@
-import { IsInt, IsNotEmpty, IsObject, IsOptional, IsString } from "class-validator";
+import { IsInt, IsNotEmpty, IsObject, IsOptional, IsPositive, IsString } from "class-validator";
 
 /**
  * Defines the runner group class - a simplified version of the backend's ResponseRunnerTeam/-Organization
 */
-export abstract class RunnerGroup {
+export class RunnerGroup {
     /**
      * The group's id.
      */
     @IsInt()
-    @IsNotEmpty()
-    id: number;;
+    @IsPositive()
+    id: number;
 
     /**
      * The group's name.