refactor(traverse): add debug asserts for safety invariants

crates/oxc_traverse/src/context/ancestry.rs

@@ -45,6 +45,7 @@ impl<'a> TraverseAncestry<'a> {
     /// Get parent of current node.
     #[inline]
     pub fn parent<'t>(&'t self) -> Ancestor<'a, 't> {
+        debug_assert!(!self.stack.is_empty());
         // SAFETY: Stack contains 1 entry initially. Entries are pushed as traverse down the AST,
         // and popped as go back up. So even when visiting `Program`, the initial entry is in the stack.
         let ancestor = unsafe { *self.stack.last().unwrap_unchecked() };
@@ -117,6 +118,7 @@ impl<'a> TraverseAncestry<'a> {
     /// This method must not be public outside this crate, or consumer could break safety invariants.
     #[inline]
     pub(crate) unsafe fn pop_stack(&mut self) {
+        debug_assert!(!self.stack.is_empty());
         self.stack.pop().unwrap_unchecked();
     }
 
@@ -143,6 +145,7 @@ impl<'a> TraverseAncestry<'a> {
     #[inline]
     #[allow(unsafe_code, clippy::ptr_as_ptr, clippy::ref_as_ptr)]
     pub(crate) unsafe fn retag_stack(&mut self, ty: AncestorType) {
+        debug_assert!(!self.stack.is_empty());
         *(self.stack.last_mut().unwrap_unchecked() as *mut _ as *mut AncestorType) = ty;
     }
 }