store: keys_at tells no map from an empty one

registry::exists counted any value at _continuum/users as a registry;
keys_at answers None where there is no map, and its users (records,
members, forget records, remakes) say what they make of it.

Auth plan M1 (fix).

3 files changed, 8 insertions, 3 deletions

diff --git a/src/remake/delta.rs b/src/remake/delta.rs
index 638231c..6864c4d 100644
--- a/src/remake/delta.rs
+++ b/src/remake/delta.rs
@@ -242,8 +242,8 @@ fn replay_path(
     // Replacing an ancestor of the protocol metadata as a whole would clobber it; replay
     // its children one by one instead.
     if contains_protocol_path(path) {
-        let mut keys = store::keys_at(src, path).unwrap_or_default();
-        keys.extend(store::keys_at(dst, path).unwrap_or_default());
+        let mut keys = store::keys_at(src, path).ok().flatten().unwrap_or_default();
+        keys.extend(store::keys_at(dst, path).ok().flatten().unwrap_or_default());
         keys.sort();
         keys.dedup();
         for key in keys {
diff --git a/src/remake/records.rs b/src/remake/records.rs
index 0c4c444..21b383c 100644
--- a/src/remake/records.rs
+++ b/src/remake/records.rs
@@ -360,6 +360,8 @@ pub(crate) fn load(doc: &impl ReadDoc, id: &str) -> Option<Record> {
 pub(crate) fn load_all(doc: &impl ReadDoc) -> Vec<(String, Record)> {
     let register = load_register(doc);
     store::keys_at(doc, &records_dir())
+        .ok()
+        .flatten()
         .unwrap_or_default()
         .into_iter()
         .filter_map(|id| {
@@ -434,6 +436,8 @@ fn register_path(voter: &str) -> Vec<String> {
 /// The votes register; unreadable entries are skipped with a warning.
 pub(crate) fn load_register(doc: &impl ReadDoc) -> Register {
     store::keys_at(doc, &meta::path(&[VOTES]))
+        .ok()
+        .flatten()
         .unwrap_or_default()
         .into_iter()
         .filter_map(|voter| {
diff --git a/src/remake/snapshot.rs b/src/remake/snapshot.rs
index 157a28d..220989e 100644
--- a/src/remake/snapshot.rs
+++ b/src/remake/snapshot.rs
@@ -231,6 +231,7 @@ pub(crate) fn verify_document(doc: &Document, epoch: Epoch) -> Result<EpochMetad
 pub(crate) fn epoch_of(doc: &Document) -> Result<Epoch, String> {
     let generation = store::keys_at(doc, &meta::path(&[EPOCHS]))
         .map_err(|error| error.to_string())?
+        .unwrap_or_default()
         .iter()
         .filter_map(|key| key.parse::<u64>().ok())
         .max();
@@ -295,7 +296,7 @@ pub(crate) fn build(
         Ok(()) | Err(StoreError::NotFound) => {}
         Err(error) => return Err(error.into()),
     }
-    let mut protocol_keys = store::keys_at(&base, &meta::path(&[]))?;
+    let mut protocol_keys = store::keys_at(&base, &meta::path(&[]))?.unwrap_or_default();
     protocol_keys.sort();
     for key in protocol_keys
         .into_iter()