add_user, add_group features.

src/errors.rs

@@ -0,0 +1,29 @@
+use rusqlite::Error as sqlite_error;
+use rusqlite::{named_params, params, Connection, Result};
+use telegram_bot::Error as tg_error;
+use std::{fmt, io};
+
+#[derive(Debug)]
+pub(crate) enum Error {
+    UserNotFound,
+    SQLITE3Error(sqlite_error),
+    TelegramError(tg_error),
+    ConfNotFound,
+}
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "An error occurred.")
+    }
+}
+
+impl From<sqlite_error> for Error {
+    fn from(e: sqlite_error) -> Error {
+        return Error::SQLITE3Error(e);
+    }
+}
+
+impl From<tg_error> for Error {
+    fn from(e: tg_error) -> Error {
+        return Error::TelegramError(e);
+    }
+}