improve all error message

Author: irevoire

src/error.rs

@@ -1,6 +1,6 @@
 use std::io;
 
-use crate::key::Key;
+use crate::{key::Key, node_id::NodeMode, ItemId};
 
 /// The different set of errors that arroy can encounter.
 #[derive(Debug, thiserror::Error)]
@@ -52,6 +52,27 @@ pub enum Error {
     NeedBuild(u16),
 
     /// Internal error
-    #[error("Internal error: {:?} is missing in index `{}`", .0.node, .0.index)]
-    MissingKey(Key),
+    #[error("Internal error: {mode}({item}) is missing in index `{index}`")]
+    MissingKey {
+        /// The index that caused the error
+        index: u16,
+        /// The kind of item that was being queried
+        mode: &'static str,
+        /// The item ID queried
+        item: ItemId,
+    },
+}
+
+impl Error {
+    pub(crate) fn missing_key(key: Key) -> Self {
+        Self::MissingKey {
+            index: key.index,
+            mode: match key.node.mode {
+                NodeMode::Item => "Item",
+                NodeMode::Tree => "Tree",
+                NodeMode::Metadata => "Metadata",
+            },
+            item: key.node.item,
+        }
+    }
 }

src/reader.rs

@@ -228,7 +228,7 @@ impl<'t, D: Distance> Reader<'t, D> {
             };
 
             let key = Key::new(self.index, item);
-            match self.database.get(rtxn, &key)?.ok_or(Error::MissingKey(key))? {
+            match self.database.get(rtxn, &key)?.ok_or(Error::missing_key(key))? {
                 Node::Leaf(_) => {
                     if candidates.map_or(true, |c| c.contains(item.item)) {
                         nns.push(item.unwrap_item());
@@ -257,7 +257,7 @@ impl<'t, D: Distance> Reader<'t, D> {
         let mut nns_distances = Vec::with_capacity(nns.len());
         for nn in nns {
             let key = Key::item(self.index, nn);
-            let leaf = match self.database.get(rtxn, &key)?.ok_or(Error::MissingKey(key))? {
+            let leaf = match self.database.get(rtxn, &key)?.ok_or(Error::missing_key(key))? {
                 Node::Leaf(leaf) => leaf,
                 Node::Descendants(_) | Node::SplitPlaneNormal(_) => unreachable!(),
             };

src/tests/reader.rs

@@ -34,7 +34,7 @@ fn open_unfinished_db() {
 
     let rtxn = handle.env.read_txn().unwrap();
     let ret = Reader::<Euclidean>::open(&rtxn, 0, handle.database).map(|_| ()).unwrap_err();
-    insta::assert_display_snapshot!(ret, @"Metadata are missing on index 0, did you build your database before trying to read it.");
+    insta::assert_display_snapshot!(ret, @"Metadata are missing on index 0, did you build your database before trying to read it");
 }
 
 #[test]
@@ -50,7 +50,7 @@ fn open_db_with_wrong_dimension() {
     let rtxn = handle.env.read_txn().unwrap();
     let reader = Reader::<Euclidean>::open(&rtxn, 0, handle.database).unwrap();
     let ret = reader.nns_by_vector(&rtxn, &[1.0, 2.0, 3.0], 5, None, None).unwrap_err();
-    insta::assert_display_snapshot!(ret, @"Invalid vector dimensions. Got 3 but expected 2.");
+    insta::assert_display_snapshot!(ret, @"Invalid vector dimensions. Got 3 but expected 2");
 }
 
 #[test]

src/writer.rs

@@ -775,7 +775,7 @@ impl<D: Distance> Writer<D> {
 
     fn delete_tree(&self, wtxn: &mut RwTxn, node: NodeId) -> Result<()> {
         let key = Key::new(self.index, node);
-        match self.database.get(wtxn, &key)?.ok_or(Error::MissingKey(key))? {
+        match self.database.get(wtxn, &key)?.ok_or(Error::missing_key(key))? {
             // the leafs are shared between the trees, we MUST NOT delete them.
             Node::Leaf(_) => Ok(()),
             Node::Descendants(_) => {