diff --git a/ext/stats/stats.go b/ext/stats/stats.go
index 452ebc8..69371c4 100644
--- a/ext/stats/stats.go
+++ b/ext/stats/stats.go
@@ -177,14 +177,14 @@ func (fn *covariance) Value(ctx sqlite3.Context) {
 }
 
 func (fn *covariance) Step(ctx sqlite3.Context, arg ...sqlite3.Value) {
-	a, b := arg[0], arg[1]
+	b, a := arg[1], arg[0] // avoid a bounds check
 	if a.NumericType() != sqlite3.NULL && b.NumericType() != sqlite3.NULL {
 		fn.enqueue(a.Float(), b.Float())
 	}
 }
 
 func (fn *covariance) Inverse(ctx sqlite3.Context, arg ...sqlite3.Value) {
-	a, b := arg[0], arg[1]
+	b, a := arg[1], arg[0] // avoid a bounds check
 	if a.NumericType() != sqlite3.NULL && b.NumericType() != sqlite3.NULL {
 		fn.dequeue(a.Float(), b.Float())
 	}
diff --git a/sqlite.go b/sqlite.go
index b8c06d6..f91fdcb 100644
--- a/sqlite.go
+++ b/sqlite.go
@@ -131,7 +131,7 @@ func (sqlt *sqlite) error(rc uint64, handle uint32, sql ...string) error {
 			err.msg = util.ReadString(sqlt.mod, uint32(r), _MAX_LENGTH)
 		}
 
-		if sql != nil {
+		if len(sql) != 0 {
 			if r := sqlt.call("sqlite3_error_offset", uint64(handle)); r != math.MaxUint32 {
 				err.sql = sql[0][r:]
 			}
diff --git a/stmt.go b/stmt.go
index e61ea1e..ada07c8 100644
--- a/stmt.go
+++ b/stmt.go
@@ -640,9 +640,7 @@ func (s *Stmt) Columns(dest []any) error {
 
 	types := util.View(s.c.mod, typePtr, count)
 
-	// hint to the compiler that
-	// it can omit bounds check
-	// accessing types[i] below.
+	// Avoid bounds checks on types below.
 	if len(types) != len(dest) {
 		panic(util.AssertErr())
 	}