refactor: split database into multiple files, more error handling, cleaner code

src/error.rs

@@ -0,0 +1,36 @@
+use thiserror::Error;
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error("problem with the database")]
+    SledError {
+        #[from]
+        source: sled::Error,
+    },
+    #[error("tried to parse invalid string")]
+    StringFromBytesError {
+        #[from]
+        source: std::string::FromUtf8Error,
+    },
+    #[error("tried to parse invalid identifier")]
+    SerdeJsonError {
+        #[from]
+        source: serde_json::Error,
+    },
+    #[error("tried to parse invalid identifier")]
+    RumaIdentifierError {
+        #[from]
+        source: ruma_identifiers::Error,
+    },
+    #[error("tried to parse invalid event")]
+    RumaEventError {
+        #[from]
+        source: ruma_events::InvalidEvent,
+    },
+    #[error("bad request")]
+    BadRequest(&'static str),
+    #[error("problem in that database")]
+    BadDatabase(&'static str),
+}