Simplify SQL error handling (#2415)

* Remove sql::error submodule

Use anyhow errors instead.

* Remove explicit checks for open SQL connection

An error will be thrown anyway during attempt to execute query.

* Don't use `with_conn()` and remove it

* Remove unused `with_conn_async`

* Resultify markseen_msgs

src/sql/error.rs

@@ -1,21 +0,0 @@
-#[derive(Debug, thiserror::Error)]
-pub enum Error {
-    #[error("Sqlite error: {0:?}")]
-    Sql(#[from] rusqlite::Error),
-    #[error("Sqlite Connection Pool Error: {0:?}")]
-    ConnectionPool(#[from] r2d2::Error),
-    #[error("Sqlite: Connection closed")]
-    SqlNoConnection,
-    #[error("Sqlite: Already open")]
-    SqlAlreadyOpen,
-    #[error("Sqlite: Failed to open")]
-    SqlFailedToOpen,
-    #[error("{0}")]
-    Io(#[from] std::io::Error),
-    // #[error("{0:?}")]
-    // BlobError(#[from] crate::blob::BlobError),
-    #[error("{0}")]
-    Other(#[from] anyhow::Error),
-}
-
-pub type Result<T> = std::result::Result<T, Error>;

src/sql/migrations.rs

@@ -1,10 +1,12 @@
-use super::{Result, Sql};
+use anyhow::Result;
+
 use crate::config::Config;
 use crate::constants::ShowEmails;
 use crate::context::Context;
 use crate::dc_tools::EmailAddress;
 use crate::imap;
 use crate::provider::get_provider_by_domain;
+use crate::sql::Sql;
 
 const DBVERSION: i32 = 68;
 const VERSION_CFG: &str = "dbversion";