cmd, core/state, eth, tests, trie: improve state reader (#27428)

The state availability is checked during the creation of a state reader.

-    In hash-based database, if the specified root node does not exist on disk disk, then
    the state reader won't be created and an error will be returned.

-    In path-based database, if the specified state layer is not available, then the
    state reader won't be created and an error will be returned.

This change also contains a stricter semantics regarding the `Commit` operation: once it has been performed, the trie is no longer usable, and certain operations will return an error.

eth/api_debug.go

@@ -235,7 +235,11 @@ func (api *DebugAPI) StorageRangeAt(ctx context.Context, blockNrOrHash rpc.Block
 }
 
 func storageRangeAt(st state.Trie, start []byte, maxResult int) (StorageRangeResult, error) {
-	it := trie.NewIterator(st.NodeIterator(start))
+	trieIt, err := st.NodeIterator(start)
+	if err != nil {
+		return StorageRangeResult{}, err
+	}
+	it := trie.NewIterator(trieIt)
 	result := StorageRangeResult{Storage: storageMap{}}
 	for i := 0; i < maxResult && it.Next(); i++ {
 		_, content, _, err := rlp.Split(it.Value)
@@ -326,7 +330,15 @@ func (api *DebugAPI) getModifiedAccounts(startBlock, endBlock *types.Block) ([]c
 	if err != nil {
 		return nil, err
 	}
-	diff, _ := trie.NewDifferenceIterator(oldTrie.NodeIterator([]byte{}), newTrie.NodeIterator([]byte{}))
+	oldIt, err := oldTrie.NodeIterator([]byte{})
+	if err != nil {
+		return nil, err
+	}
+	newIt, err := newTrie.NodeIterator([]byte{})
+	if err != nil {
+		return nil, err
+	}
+	diff, _ := trie.NewDifferenceIterator(oldIt, newIt)
 	iter := trie.NewIterator(diff)
 
 	var dirty []common.Address