fix: use tagged enum serialization for TankError

rust/src/main.rs

@@ -307,7 +307,7 @@ async fn safe_main(spawner: Spawner) -> FatResult<()> {
         if let Some(err) = tank_state.got_error(&board.board_hal.get_config().tank) {
             match err {
                 TankError::SensorDisabled => { /* unreachable */ }
-                TankError::SensorMissing(raw_value_mv) => log(
+                TankError::SensorMissing { raw_mv: raw_value_mv } => log(
                     LogMessage::TankSensorMissing,
                     raw_value_mv as u32,
                     0,
@@ -321,8 +321,8 @@ async fn safe_main(spawner: Spawner) -> FatResult<()> {
                     &format!("{value}"),
                     "",
                 ),
-                TankError::BoardError(err) => {
-                    log(LogMessage::TankSensorBoardError, 0, 0, "", &err.to_string())
+                TankError::BoardError { message: err } => {
+                    log(LogMessage::TankSensorBoardError, 0, 0, "", &err)
                 }
             }
             // disabled cannot trigger this because of wrapping if is_enabled

rust/src/tank.rs

@@ -10,11 +10,12 @@ const OPEN_TANK_VOLTAGE: f32 = 3.0;
 pub const WATER_FROZEN_THRESH: f32 = 4.0;
 
 #[derive(Debug, Clone, Serialize)]
+#[serde(tag = "kind")]
 pub enum TankError {
     SensorDisabled,
-    SensorMissing(f32),
+    SensorMissing { raw_mv: f32 },
     SensorValueError { value: f32, min: f32, max: f32 },
-    BoardError(String),
+    BoardError { message: String },
 }
 
 pub enum TankState {
@@ -25,7 +26,7 @@ pub enum TankState {
 
 fn raw_voltage_to_divider_percent(raw_value_mv: f32) -> Result<f32, TankError> {
     if raw_value_mv > OPEN_TANK_VOLTAGE {
-        return Err(TankError::SensorMissing(raw_value_mv));
+        return Err(TankError::SensorMissing { raw_mv: raw_value_mv });
     }
 
     let r2 = raw_value_mv * 50.0 / (3.3 - raw_value_mv);
@@ -164,7 +165,7 @@ pub async fn determine_tank_state(
             .and_then(|f| core::prelude::v1::Ok(f.tank_sensor_voltage()))
         {
             Ok(raw_sensor_value_mv) => TankState::Present(raw_sensor_value_mv.await.unwrap()),
-            Err(err) => TankState::Error(TankError::BoardError(err.to_string())),
+            Err(err) => TankState::Error(TankError::BoardError { message: err.to_string() }),
         }
     } else {
         TankState::Disabled