diff --git a/ufos/src/bin/analyze.rs b/ufos/src/bin/analyze.rs
index 384536c..7984939 100644
--- a/ufos/src/bin/analyze.rs
+++ b/ufos/src/bin/analyze.rs
@@ -6,8 +6,8 @@ use std::collections::BTreeMap;
 use std::path::PathBuf;
 use ufos::db_types::{db_complete, DbBytes};
 use ufos::store_types::{
-    AllTimeRollupKey, AllTimeRollupStaticPrefix, CountsValue, WeekTruncatedCursor,
-    WeeklyRollupKey, WeeklyRollupStaticPrefix, WithCollection,
+    AllTimeRollupKey, AllTimeRollupStaticPrefix, CountsValue, WeekTruncatedCursor, WeeklyRollupKey,
+    WeeklyRollupStaticPrefix, WithCollection,
 };
 
 #[derive(Parser)]
@@ -69,6 +69,7 @@ fn total_users(rollups: &PartitionHandle) -> anyhow::Result<()> {
 
 /// Scan weekly rollups once, returning week -> (merged sketch, per-group entries)
 /// Only non-excluded groups are included.
+#[expect(clippy::type_complexity)]
 fn scan_weekly(
     rollups: &PartitionHandle,
 ) -> anyhow::Result<BTreeMap<u64, (Sketch<14>, Vec<(String, u64)>)>> {
@@ -94,7 +95,7 @@ fn scan_weekly(
         }
 
         scanned += 1;
-        if scanned % 500_000 == 0 {
+        if scanned.is_multiple_of(500_000) {
             eprintln!("  ...scanned {scanned} weekly entries");
         }
     }
diff --git a/ufos/src/error.rs b/ufos/src/error.rs
index 012b61d..6b7748a 100644
--- a/ufos/src/error.rs
+++ b/ufos/src/error.rs
@@ -28,11 +28,11 @@ pub enum StorageError {
     InitError(String),
     #[error("DB seems to be in a bad state: {0}")]
     BadStateError(String),
-    #[error("Fjall error")]
+    #[error("Fjall error: {0}")]
     FjallError(#[from] fjall::Error),
-    #[error("LSM-tree error (from fjall)")]
+    #[error("LSM-tree error (from fjall): {0}")]
     FjallLsmError(#[from] fjall::LsmError),
-    #[error("Bytes encoding error")]
+    #[error("Bytes encoding error: {0}")]
     EncodingError(#[from] EncodingError),
     #[error("If you ever see this, there's a bug in the code. The error was stolen")]
     Stolen,
diff --git a/ufos/src/storage_fjall.rs b/ufos/src/storage_fjall.rs
index ec46301..dc96c45 100644
--- a/ufos/src/storage_fjall.rs
+++ b/ufos/src/storage_fjall.rs
@@ -1205,7 +1205,7 @@ impl FjallWriter {
 
         let mut dirty_nsids = HashSet::new();
 
-        #[derive(Eq, Hash, PartialEq)]
+        #[derive(Debug, Eq, Hash, PartialEq)]
         enum Rollup {
             Hourly(HourTruncatedCursor),
             Weekly(WeekTruncatedCursor),
@@ -1235,7 +1235,9 @@ impl FjallWriter {
             dirty_nsids.insert(key.collection().clone());
 
             batch.remove(&self.rollups, key_bytes);
-            let val = db_complete::<CountsValue>(&val_bytes)?;
+            let val = db_complete::<CountsValue>(&val_bytes).inspect_err(|e| {
+                log::error!("bad CountsValue at {key:?} from rolling up timelies: {e}")
+            })?;
             counts_by_rollup
                 .entry((
                     key.collection().clone(),
@@ -1275,7 +1277,10 @@ impl FjallWriter {
                 .get(&rollup_key_bytes)?
                 .as_deref()
                 .map(db_complete::<CountsValue>)
-                .transpose()?
+                .transpose()
+                .inspect_err(|e| {
+                    log::error!("bad CountsValue at {nsid:?}/{rollup:?} from counts_by_rollup: {e}")
+                })?
                 .unwrap_or_default();
 
             // now that we have values, we can know the exising ranks