fix(treesitter): #has-parent? errors on a node with no parent

Problem:
The #has-parent? predicate indexes the result of node:parent() without
checking it, so a capture that matches a tree's root node raises

    query.lua:600: attempt to index a nil value

instead of simply not matching. In a highlights query that breaks
highlighting for the whole buffer. The sibling #has-ancestor? predicate
handles the same situation.

Solution:
Treat a missing parent as "does not match".

AI-assisted

runtime/lua/vim/treesitter/query.lua

@@ -597,7 +597,8 @@ local predicate_handlers = {
     end
 
     for _, node in ipairs(nodes) do
-      if vim.list_contains({ unpack(predicate, 3) }, node:parent():type()) then
+      local parent = node:parent()
+      if parent and vim.list_contains({ unpack(predicate, 3) }, parent:type()) then
         return true
       end
     end

test/functional/treesitter/query_spec.lua

@@ -452,6 +452,26 @@ void ui_refresh(void)
     eq({}, result)
   end)
 
+  it('supports builtin predicate has-parent?', function()
+    insert([[
+      int x = 123;
+      enum C { y = 124 };]])
+
+    local result = exec_lua(
+      get_query_result,
+      [[((number_literal) @literal (#has-parent? @literal "init_declarator"))]]
+    )
+    eq({ { 'literal', 'number_literal', { 0, 8, 0, 11 }, '123' } }, result)
+
+    -- The root node has no parent: the predicate does not match, rather than
+    -- erroring on the nil parent.
+    result = exec_lua(
+      get_query_result,
+      [[((translation_unit) @root (#has-parent? @root "translation_unit"))]]
+    )
+    eq({}, result)
+  end)
+
   it('allows loading query with escaped quotes and capture them `#{lua,vim}-match`?', function()
     insert('char* astring = "Hello World!";')