Add asynchronous call to database.

See file 'asynchronous.ts'.

backend/src/utils.rs

@@ -0,0 +1,11 @@
+use log::error;
+
+pub fn unwrap_print_err<T, E>(r: Result<T, E>) -> T
+where
+    E: std::fmt::Debug
+{
+    if let Err(ref error) = r {
+        error!("{:?}", error);
+    }
+    r.unwrap()
+}