refactor(sql): do not expose rusqlite Error type in query_map methods

We use query_and_then() instead of query_map() function now.
The difference is that row processing function
returns anyhow::Result, so simple fallible processing
like JSON parsing can be done inside of it
when calling query_map_vec() and query_map_collect()
without having to resort to query_map()
and iterating over all rows again afterwards.

src/stats.rs

@@ -378,7 +378,10 @@ async fn get_timestamps(context: &Context, sql_table: &str) -> Result<Vec<i64>>
         .query_map_vec(
             &format!("SELECT timestamp FROM {sql_table} LIMIT 1000"),
             (),
-            |row| row.get(0),
+            |row| {
+                let timestamp: i64 = row.get(0)?;
+                Ok(timestamp)
+            },
         )
         .await
 }