[bugfix] Sqlite transaction escalation was causing errors (#6299)

* well that was an easy fix

* change fn name because somebody wasn't happy about my one line fix

common/credential-storage/src/backends/sqlite.rs

@@ -40,8 +40,11 @@ impl SqliteEcashTicketbookManager {
         Ok(())
     }
 
-    pub(crate) async fn begin_storage_tx(&self) -> Result<Transaction<'_, Sqlite>, sqlx::Error> {
-        self.connection_pool.begin().await
+    /// Starts a write (IMMEDIATE) transaction, to prevent issue when upgrading from a read one to a write one
+    pub(crate) async fn begin_storage_write_tx(
+        &self,
+    ) -> Result<Transaction<'_, Sqlite>, sqlx::Error> {
+        self.connection_pool.begin_with("BEGIN IMMEDIATE").await
     }
 
     pub(crate) async fn insert_pending_ticketbook(

common/credential-storage/src/persistent_storage/mod.rs

@@ -244,7 +244,7 @@ impl Storage for PersistentStorage {
         tickets: u32,
     ) -> Result<Option<RetrievedTicketbook>, Self::StorageError> {
         let deadline = ecash_today().ecash_date();
-        let mut tx = self.storage_manager.begin_storage_tx().await?;
+        let mut tx = self.storage_manager.begin_storage_write_tx().await?;
 
         // we don't want ticketbooks with expiration in the past
         let Some(raw) =