refactor: error handling (#41)

mini-lsm-starter/src/lsm_iterator.rs

@@ -46,11 +46,15 @@ impl StorageIterator for LsmIterator {
 /// `is_valid` should return false, and `next` should always return an error.
 pub struct FusedIterator<I: StorageIterator> {
     iter: I,
+    has_errored: bool,
 }
 
 impl<I: StorageIterator> FusedIterator<I> {
     pub fn new(iter: I) -> Self {
-        Self { iter }
+        Self {
+            iter,
+            has_errored: false,
+        }
     }
 }
 

mini-lsm/src/lsm_iterator.rs

@@ -106,14 +106,14 @@ impl<I: StorageIterator> StorageIterator for FusedIterator<I> {
     }
 
     fn key(&self) -> Self::KeyType<'_> {
-        if self.has_errored || !self.iter.is_valid() {
+        if !self.is_valid() {
             panic!("invalid access to the underlying iterator");
         }
         self.iter.key()
     }
 
     fn value(&self) -> &[u8] {
-        if self.has_errored || !self.iter.is_valid() {
+        if !self.is_valid() {
             panic!("invalid access to the underlying iterator");
         }
         self.iter.value()