diff --git a/frontend/src/components/Checkpoint/checkpoint.ts b/frontend/src/components/Checkpoint/checkpoint.ts
index 9e642cf..c2b46d9 100644
--- a/frontend/src/components/Checkpoint/checkpoint.ts
+++ b/frontend/src/components/Checkpoint/checkpoint.ts
@@ -1,23 +1,30 @@
 type Checkpoints = Map<string, Set<string>>;
 
 class Persistent {
-  persistent: Checkpoints = new Map<string, Set<string>>();
+  persistent: Checkpoints = new Map();
   subscribers: Array<(checkpoints: Checkpoints) => void> = [];
 
   constructor() {
     this.persistent = this.deserialize();
   }
-
+  
   private serialize() {
     const serialized: Array<[string, string[]]> = [
       ...this.persistent.entries(),
     ].map(([k, v]) => [k, Array.from(v)]);
     localStorage.setItem("checkpoints", JSON.stringify(serialized));
   }
-
+  
+  /* Old format
+    {"data":[["#$@__reference__1","1",{"data":["1-1"],"#$@__constructor__":"Set","#$@__reference__":2}],["#$@__reference__3","2",{"data":["2-1","2-2","2-3","2-4","2-5","2-6","2-7","2-8","2-confetti"],"#$@__constructor__":"Set","#$@__reference__":4}],["#$@__reference__5","3",{"data":["3-1"],"#$@__constructor__":"Set","#$@__reference__":6}],["#$@__reference__7","4",{"data":["4-1"],"#$@__constructor__":"Set","#$@__reference__":8}]],"#$@__constructor__":"Map","#$@__reference__":0} 
+  */
   private deserialize(): Checkpoints {
     const item = localStorage.getItem("checkpoints") as string;
     const parsed: Array<[string, string[]]> = (item && JSON.parse(item)) || [];
+    if (!Array.isArray(parsed)) {
+      window.alert("Failed to load checkpoints, resetting progress.")
+      return new Map();
+    }
     return new Map(parsed.map(([k, v]) => [k, new Set(v)]));
   }
 
diff --git a/frontend/src/content/docs/en/first-steps/4-enrolling.mdx b/frontend/src/content/docs/en/first-steps/4-enrolling.mdx
index ba0fd1d..c093d1b 100644
--- a/frontend/src/content/docs/en/first-steps/4-enrolling.mdx
+++ b/frontend/src/content/docs/en/first-steps/4-enrolling.mdx
@@ -42,7 +42,7 @@ Please fill in the remaining information in the blanks provided:
 </Guild>
 
 :::caution[Data collection?]
-**DATA WILL NOT BE COLLECTED** in any way, it's just an exercise.  
+**DATA WILL NOT BE COLLECTED** in any way, it's just for the exercise.  
 If you're worried about it, use dummy values that don't match your real data.
 :::