treat empty membership pdf as non-existing

src/model/user.rs

@@ -989,12 +989,16 @@ pub struct UserWithRolesAndMembershipPdf {
 
 impl UserWithRolesAndMembershipPdf {
     pub(crate) async fn from_user(db: &SqlitePool, user: User) -> Self {
-        let membership_pdf: bool =
-            sqlx::query_scalar!("SELECT membership_pdf FROM user WHERE id = ?", user.id)
+        let membership_pdf =
+            match sqlx::query_scalar!("SELECT membership_pdf FROM user WHERE id = ?", user.id)
                 .fetch_one(db)
                 .await
                 .unwrap()
-                .is_some();
+            {
+                Some(a) if a.is_empty() => false,
+                None => false,
+                _ => true,
+            };
 
         Self {
             roles: user.roles(db).await,