Add original database code

src/db/error.rs

@@ -0,0 +1,24 @@
+/// Error that happens within the database module.
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    Connection(#[from] diesel::result::ConnectionError),
+
+    #[error(transparent)]
+    Migrations(#[from] Box<dyn std::error::Error + Send + Sync>),
+
+    #[error(transparent)]
+    Query(#[from] diesel::result::Error),
+
+    #[error("Missing item dependency ({0} {1})")]
+    MissingItem(&'static str, String),
+
+    #[error("Failed to parse {0} from '{1}'")]
+    Parsing(&'static str, String),
+
+    #[error("{0}")]
+    Other(&'static str),
+}
+
+/// Return type for database methods.
+pub type Result<T> = std::result::Result<T, Error>;