don't save empty guard tokens

src/auth/guarddata.rs

@@ -105,14 +105,18 @@ impl GuardDataStore for FileGuardDataStore {
     type Err = FileStoreError;
 
     async fn store(&mut self, account: &str, machine_token: String) -> Result<(), Self::Err> {
-        let mut tokens = self.all_tokens()?;
-        tokens.insert(account.into(), machine_token);
-        self.save(tokens)
+        if !machine_token.is_empty() {
+            let mut tokens = self.all_tokens()?;
+            tokens.insert(account.into(), machine_token);
+            self.save(tokens)
+        } else {
+            Ok(())
+        }
     }
 
     async fn load(&mut self, account: &str) -> Result<Option<String>, Self::Err> {
         let mut tokens = self.all_tokens()?;
-        Ok(tokens.remove(account))
+        Ok(tokens.remove(account).filter(|token| !token.is_empty()))
     }
 }
 

src/auth/mod.rs

@@ -182,7 +182,7 @@ impl PendingAuth {
                 return Ok(Tokens {
                     access_token: Token(response.take_access_token()),
                     refresh_token: Token(response.take_refresh_token()),
-                    new_guard_data: response.take_new_guard_data(),
+                    new_guard_data: response.new_guard_data,
                 });
             }
         }
@@ -203,8 +203,7 @@ pub(crate) struct Tokens {
     #[allow(dead_code)]
     pub access_token: Token,
     pub refresh_token: Token,
-    #[allow(dead_code)]
-    pub new_guard_data: String,
+    pub new_guard_data: Option<String>,
 }
 
 async fn poll_until_info(

src/connection/mod.rs

@@ -120,9 +120,10 @@ impl Connection {
             Either::Right((tokens, _)) => tokens?,
         };
 
-        debug!(account, "saving guard data");
-        if let Err(e) = guard_data_store.store(account, tokens.new_guard_data).await {
-            error!(error = ?e, "failed to store guard data");
+        if let Some(guard_data) = tokens.new_guard_data {
+            if let Err(e) = guard_data_store.store(account, guard_data).await {
+                error!(error = ?e, "failed to store guard data");
+            }
         }
 
         connection.session = login(