improvement: device list works better

The only situation that isn't working yet is sending `left` events for
users when the sender leaves the room

src/utils.rs

@@ -1,4 +1,3 @@
-use crate::Error;
 use argon2::{Config, Variant};
 use cmp::Ordering;
 use rand::prelude::*;
@@ -91,8 +90,3 @@ pub fn common_elements(
             .all(|b| b)
     }))
 }
-
-pub fn deserialize<'de, T: serde::Deserialize<'de>>(val: &'de sled::IVec) -> Result<T, Error> {
-    serde_json::from_slice::<T>(val.as_ref())
-        .map_err(|_| Error::bad_database("Found invalid bytes as PDU in db."))
-}