Fix entries not being removed if ignore_before_date after the last grade

rslib/src/scheduler/fsrs/params.rs

@@ -340,6 +340,9 @@ pub(crate) fn reviews_for_fsrs(
         if idx > 0 {
             entries.drain(..idx);
         }
+    } else {
+        // if no valid user grades were found, drain all entries
+        entries.drain(..);
     }
 
     // Filter out unwanted entries
@@ -709,4 +712,19 @@ pub(crate) mod tests {
             2
         );
     }
+
+    #[test]
+    fn ignore_before_after_last_revlog_entry() {
+        let revlogs = &[
+            revlog(RevlogReviewKind::Learning, 10),
+            revlog(RevlogReviewKind::Review, 6),
+        ];
+        // L R | 
+        assert_eq!(
+            convert_ignore_before(revlogs, false, days_ago_ms(4))
+                .unwrap()
+                .len(),
+            0
+        );
+    }
 }