address most of wills review feedback, fix serialization and stringly error handling in DiagTask::start

daemon/src/main.rs

@@ -306,14 +306,12 @@ async fn run_with_config(
             config.webdav.clone().into(),
         );
     }
-    // For fixed configuration, we use timestamp 0 to not break other
-    // the GET request for GPS but user won't see the 0 in PCAPs
     let initial_gps = if config.gps_mode == GpsMode::Fixed {
         match (config.gps_fixed_latitude, config.gps_fixed_longitude) {
             (Some(lat), Some(lon)) => Some(gps::GpsData {
                 latitude: lat,
                 longitude: lon,
-                timestamp: 0,
+                timestamp: chrono::Utc::now().timestamp(),
             }),
             _ => {
                 warn!(