add compiler hints to reduce number of slice bounds checks (#158)

* add compiler hints to reduce number of slice bounds checks

* panic on assert instead of returning error for code coverage

stmt.go

@@ -639,6 +639,14 @@ 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.
+	if len(types) != len(dest) {
+		panic(util.AssertErr())
+	}
+
 	for i := range dest {
 		switch types[i] {
 		case byte(INTEGER):