fix(typescript): tighten TypeScript null safety and error handling across backend and ops UI

ts/radius/classes.radius.server.ts

@@ -310,8 +310,8 @@ export class RadiusServer {
         default:
           logger.log('debug', `RADIUS Acct Unknown status type: ${statusType}`);
       }
-    } catch (error) {
-      logger.log('error', `RADIUS accounting error: ${error.message}`);
+    } catch (error: unknown) {
+      logger.log('error', `RADIUS accounting error: ${(error as Error).message}`);
     }
 
     return { code: plugins.smartradius.ERadiusCode.AccountingResponse };