fix(treesitter): disable parsing of symbols from subtrees

The issue is that the injected trees are all processed *after* the top
level tree, so the symbols are just tacked on to the end of the list
regardless of the subtree's position in the document. This produces an
incorrect outline and also messes up the navigation commands. More work
will need to be done to figure out how to place subtrees correctly.

lua/aerial/backends/treesitter/init.lua

@@ -25,6 +25,7 @@ M.fetch_symbols_sync = function(timeout)
   local utils = require("nvim-treesitter.utils")
   local bufnr = 0
   local filetype = vim.api.nvim_buf_get_option(bufnr, "filetype")
+  local include_kind = config.get_filter_kind_map(filetype)
   local parser = parsers.get_parser(bufnr)
   local items = {}
   if not parser then
@@ -34,20 +35,24 @@ M.fetch_symbols_sync = function(timeout)
   -- This will track a loose hierarchy of recent node+items.
   -- It is used to determine node parents for the tree structure.
   local stack = {}
-
+  local top_lang = parser:lang()
   parser:for_each_tree(function(tree, lang_tree)
     local lang = lang_tree:lang()
-    local ext = extensions[lang]
-    local kind_map = language_kind_map[lang]
-    local include_kind = config.get_filter_kind_map(filetype)
+    -- TODO: we don't support parsing symbols from injected languages yet.
+    -- It's hard to put them in the correct position in the symbol tree.
+    if top_lang ~= lang then
+      return
+    end
     if not query.has_query_files(lang, "aerial") then
       return
     end
+    local ext = extensions[lang]
+    local kind_map = language_kind_map[lang]
     for match in query.iter_group_results(bufnr, "aerial", tree:root(), lang) do
       local name_node = (utils.get_at_path(match, "name") or {}).node
       local type_node = (utils.get_at_path(match, "type") or {}).node
       local loc_node = (utils.get_at_path(match, "location") or {}).node
-      local parent, parent_node, level = ext.get_parent(stack, match, type_node)
+      local parent_item, parent_node, level = ext.get_parent(stack, match, type_node)
       -- Sometimes our queries will match the same node twice.
       -- If we do (type_node == parent_node), skip all after first.
       if type_node and type_node ~= parent_node then
@@ -77,7 +82,7 @@ M.fetch_symbols_sync = function(timeout)
             kind = kind,
             name = name,
             level = level,
-            parent = parent,
+            parent = parent_item,
             lnum = row + 1,
             col = col,
           }