Fixed some stuff not getting checked against null

ref #39 gosh i sometimes hate js types

src/models/actions/UpdateRunnerTeam.ts

@@ -22,7 +22,7 @@ export class UpdateRunnerTeam extends CreateRunnerGroup {
     parentGroup: RunnerOrganisation;
 
     public async getParent(): Promise<RunnerOrganisation> {
-        if (this.parentGroup === undefined) {
+        if (this.parentGroup === undefined || this.parentGroup === null) {
             throw new RunnerTeamNeedsParentError();
         }
         if (!isNaN(this.parentGroup.id)) {