fix: make DEFAULT_COUNTRY a required field (#8891)

Author: evereq

packages/ui-config/src/lib/environments/model.ts

@@ -47,7 +47,7 @@ export interface Environment {
 	DEFAULT_LATITUDE: number;
 	DEFAULT_LONGITUDE: number;
 	DEFAULT_CURRENCY: string;
-	DEFAULT_COUNTRY?: string;
+	DEFAULT_COUNTRY: string;
 
 	IS_INTEGRATED_DESKTOP: boolean;