Correct boolean validator bug

NodeApp/src/managers/DojoBackendManager.ts

@@ -93,7 +93,7 @@ class DojoBackendManager {
             const response = await axios.post<DojoBackendResponse<Assignment>>(this.getApiUrl(ApiRoute.ASSIGNMENT_CREATE), Object.assign({
                                                                                                                                              name     : name,
                                                                                                                                              members  : JSON.stringify(members),
-                                                                                                                                             useSonar : sonar
+                                                                                                                                             useSonar : String(sonar)
                                                                                                                                          }, templateIdOrNamespace ? { template: templateIdOrNamespace } : {}));
 
             if ( verbose ) {