More tests, not found page and dashboard fixes

When post was deleted, website shows a 404 page insead of an 500 page.
Also made the dashboard empty page message more explicit.

src/routes/admin/posts.rs

@@ -9,7 +9,7 @@ use anyhow::Context;
 use askama::Template;
 use axum::{
     Extension, Form,
-    extract::State,
+    extract::{Path, State},
     response::{Html, IntoResponse, Response},
 };
 use chrono::Utc;
@@ -121,3 +121,26 @@ pub async fn create_newsletter(
     };
     insert_newsletter_issue(transaction, post_title, &template).await
 }
+
+pub async fn delete_post(
+    State(AppState {
+        connection_pool, ..
+    }): State<AppState>,
+    Path(post_id): Path<Uuid>,
+) -> Result<Response, AppError> {
+    let res = sqlx::query!("DELETE FROM posts WHERE post_id = $1", post_id)
+        .execute(&connection_pool)
+        .await
+        .context("Failed to delete post from database.")
+        .map_err(AppError::unexpected_message)?;
+    if res.rows_affected() > 1 {
+        Err(AppError::unexpected_message(anyhow::anyhow!(
+            "We could not find the post in the database."
+        )))
+    } else {
+        let template = MessageTemplate::Success {
+            message: "The subscriber has been deleted.".into(),
+        };
+        Ok(template.render().unwrap().into_response())
+    }
+}