lib/db: Fix some omitted error checks, unused variable (#7489)

lib/db/db_test.go

@@ -262,6 +262,9 @@ func TestUpdate0to3(t *testing.T) {
 			t.Fatal(err)
 		}
 		key, err = trans.keyer.GenerateDeviceFileKey(key, folder, vl.Versions[0].Device, name)
+		if err != nil {
+			t.Fatal(err)
+		}
 		fi, ok, err := trans.getFileTrunc(key, false)
 		if err != nil {
 			t.Fatal(err)

lib/db/lowlevel.go

@@ -932,6 +932,9 @@ func (db *Lowlevel) recalcMeta(folderStr string) (*metadataTracker, error) {
 		meta.addFile(protocol.GlobalDeviceID, f)
 		return true
 	})
+	if err != nil {
+		return nil, err
+	}
 
 	meta.emptyNeeded(protocol.LocalDeviceID)
 	err = t.withNeed(folder, protocol.LocalDeviceID[:], true, func(f protocol.FileIntf) bool {

lib/db/meta.go

@@ -148,10 +148,9 @@ func (m *metadataTracker) countsPtr(dev protocol.DeviceID, flag uint32) *Counts
 		// the metadatatracker, even if there's no change to the need
 		// bucket itself.
 		nkey := metaKey{dev, needFlag}
-		nidx, ok := m.indexes[nkey]
-		if !ok {
+		if _, ok := m.indexes[nkey]; !ok {
 			// Initially a new device needs everything, except deletes
-			nidx = len(m.counts.Counts)
+			nidx := len(m.counts.Counts)
 			m.counts.Counts = append(m.counts.Counts, m.allNeededCounts(dev))
 			m.indexes[nkey] = nidx
 		}

lib/db/schemaupdater.go

@@ -730,6 +730,9 @@ func (db *schemaUpdater) updateSchemaTo14(_ int) error {
 		defer t.close()
 
 		key, err = t.keyer.GenerateDeviceFileKey(key, folder, protocol.LocalDeviceID[:], nil)
+		if err != nil {
+			return err
+		}
 		it, err := t.NewPrefixIterator(key)
 		if err != nil {
 			return err