Fix/index err when not contain any reviews of type Review (#104)

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "FSRS-Optimizer"
-version = "4.27.5"
+version = "4.27.6"
 readme = "README.md"
 dependencies = [
     "matplotlib>=3.7.0",

src/fsrs_optimizer/__main__.py

@@ -60,7 +60,8 @@ def remembered_fallback_prompt(key: str, pretty: str = None):
 
         remembered_fallback_prompt("next_day", "used next day start hour")
         remembered_fallback_prompt(
-            "revlog_start_date", "the date at which before reviews will be ignored | YYYY-MM-DD"
+            "revlog_start_date",
+            "the date at which before reviews will be ignored | YYYY-MM-DD",
         )
         remembered_fallback_prompt(
             "filter_out_suspended_cards", "filter out suspended cards? (y/n)"
@@ -113,10 +114,14 @@ def remembered_fallback_prompt(key: str, pretty: str = None):
         plt.close(f)
 
     optimizer.predict_memory_states()
-    figures = optimizer.find_optimal_retention(verbose=save_graphs)
-    for i, f in enumerate(figures):
-        f.savefig(f"find_optimal_retention_{i}.png")
-        plt.close(f)
+    try:
+        figures = optimizer.find_optimal_retention(verbose=save_graphs)
+        for i, f in enumerate(figures):
+            f.savefig(f"find_optimal_retention_{i}.png")
+            plt.close(f)
+    except:
+        print("Failed to find optimal retention")
+        optimizer.optimal_retention = 0.9
 
     optimizer.preview(optimizer.optimal_retention)
 

src/fsrs_optimizer/fsrs_optimizer.py

@@ -1185,10 +1185,8 @@ def find_optimal_retention(
         state_block = dict()
         state_count = dict()
         state_duration = dict()
-        try:
-            last_state = self.state_sequence[0]
-        except:
-            return ()
+
+        last_state = self.state_sequence[0]
         state_block[last_state] = 1
         state_count[last_state] = 1
         state_duration[last_state] = self.duration_sequence[0]