7 files changed, 44 insertions, 45 deletions
diff --git a/runtime/lua/vim/_comment.lua b/runtime/lua/vim/_comment.lua
index c821f01257..de7f62632c 100644
--- a/runtime/lua/vim/_comment.lua
+++ b/runtime/lua/vim/_comment.lua
@@ -9,7 +9,7 @@
 local function get_commentstring(ref_position)
   local buf_cs = vim.bo.commentstring
 
-  local ts_parser = vim.treesitter._get_parser()
+  local ts_parser = vim.treesitter.get_parser(0, '', { error = false })
   if not ts_parser then
     return buf_cs
   end
diff --git a/runtime/lua/vim/treesitter.lua b/runtime/lua/vim/treesitter.lua
index baf47482a8..8d5cd2eeec 100644
--- a/runtime/lua/vim/treesitter.lua
+++ b/runtime/lua/vim/treesitter.lua
@@ -74,15 +74,21 @@ end
 
 --- Returns the parser for a specific buffer and attaches it to the buffer
 ---
---- If needed, this will create the parser. If no parser can be found or created, returns `nil`.
+--- If needed, this will create the parser.
+---
+--- If no parser can be created, an error is thrown. Set `opts.error = false` to suppress this and
+--- return nil (and an error message) instead. WARNING: This behavior will become default in Nvim
+--- 0.12 and the option will be removed.
 ---
 ---@param bufnr (integer|nil) Buffer the parser should be tied to (default: current buffer)
 ---@param lang (string|nil) Language of this parser (default: from buffer filetype)
 ---@param opts (table|nil) Options to pass to the created language tree
 ---
----@return vim.treesitter.LanguageTree? object to use for parsing, or `nil` if not found
-function M._get_parser(bufnr, lang, opts)
+---@return vim.treesitter.LanguageTree? object to use for parsing
+---@return string? error message, if applicable
+function M.get_parser(bufnr, lang, opts)
   opts = opts or {}
+  local should_error = opts.error == nil or opts.error
 
   if bufnr == nil or bufnr == 0 then
     bufnr = api.nvim_get_current_buf()
@@ -94,12 +100,22 @@ function M._get_parser(bufnr, lang, opts)
 
   if not valid_lang(lang) then
     if not parsers[bufnr] then
-      return nil
+      local err_msg =
+        string.format('Parser not found for buffer %s: language could not be determined', bufnr)
+      if should_error then
+        error(err_msg)
+      end
+      return nil, err_msg
     end
   elseif parsers[bufnr] == nil or parsers[bufnr]:lang() ~= lang then
     local parser = vim.F.npcall(M._create_parser, bufnr, lang, opts)
     if not parser then
-      return nil
+      local err_msg =
+        string.format('Parser could not be created for buffer %s and language "%s"', bufnr, lang)
+      if should_error then
+        error(err_msg)
+      end
+      return nil, err_msg
     end
     parsers[bufnr] = parser
   end
@@ -109,29 +125,6 @@ function M._get_parser(bufnr, lang, opts)
   return parsers[bufnr]
 end
 
---- Returns the parser for a specific buffer and attaches it to the buffer
----
---- If needed, this will create the parser.
----
----@param bufnr (integer|nil) Buffer the parser should be tied to (default: current buffer)
----@param lang (string|nil) Language of this parser (default: from buffer filetype)
----@param opts (table|nil) Options to pass to the created language tree
----
----@return vim.treesitter.LanguageTree object to use for parsing
-function M.get_parser(bufnr, lang, opts)
-  -- TODO(ribru17): Remove _get_parser and move that logic back here once the breaking function
-  -- signature change is acceptable.
-  local parser = M._get_parser(bufnr, lang, opts)
-  if not parser then
-    vim.notify_once(
-      'WARNING: vim.treesitter.get_parser will return nil instead of raising an error in Neovim 0.12',
-      vim.log.levels.WARN
-    )
-    error('Parser not found.')
-  end
-  return parser
-end
-
 --- Returns a string parser
 ---
 ---@param str string Text to parse
@@ -397,7 +390,7 @@ function M.get_node(opts)
 
   local ts_range = { row, col, row, col }
 
-  local root_lang_tree = M._get_parser(bufnr, opts.lang)
+  local root_lang_tree = M.get_parser(bufnr, opts.lang, { error = false })
   if not root_lang_tree then
     return
   end
@@ -430,11 +423,7 @@ end
 ---@param lang (string|nil) Language of the parser (default: from buffer filetype)
 function M.start(bufnr, lang)
   bufnr = bufnr or api.nvim_get_current_buf()
-  local parser = M._get_parser(bufnr, lang)
-  if not parser then
-    vim.notify('No parser for the given buffer.', vim.log.levels.WARN)
-    return
-  end
+  local parser = assert(M.get_parser(bufnr, lang, { error = false }))
   M.highlighter.new(parser)
 end
 
diff --git a/runtime/lua/vim/treesitter/_fold.lua b/runtime/lua/vim/treesitter/_fold.lua
index 49792c3891..7237d2e7d4 100644
--- a/runtime/lua/vim/treesitter/_fold.lua
+++ b/runtime/lua/vim/treesitter/_fold.lua
@@ -114,7 +114,7 @@ local function compute_folds_levels(bufnr, info, srow, erow, parse_injections)
   srow = srow or 0
   erow = erow or api.nvim_buf_line_count(bufnr)
 
-  local parser = assert(ts._get_parser(bufnr))
+  local parser = assert(ts.get_parser(bufnr, nil, { error = false }))
 
   parser:parse(parse_injections and { srow, erow } or nil)
 
@@ -392,7 +392,7 @@ function M.foldexpr(lnum)
   lnum = lnum or vim.v.lnum
   local bufnr = api.nvim_get_current_buf()
 
-  local parser = ts._get_parser(bufnr)
+  local parser = ts.get_parser(bufnr, nil, { error = false })
   if not parser then
     return '0'
   end
diff --git a/runtime/lua/vim/treesitter/_query_linter.lua b/runtime/lua/vim/treesitter/_query_linter.lua
index 417b8bafbb..632d045293 100644
--- a/runtime/lua/vim/treesitter/_query_linter.lua
+++ b/runtime/lua/vim/treesitter/_query_linter.lua
@@ -177,7 +177,7 @@ function M.lint(buf, opts)
       is_first_lang = i == 1,
     }
 
-    local parser = assert(vim.treesitter._get_parser(buf), 'query parser not found.')
+    local parser = assert(vim.treesitter.get_parser(buf, nil, { error = false }))
     parser:parse()
     parser:for_each_tree(function(tree, ltree)
       if ltree:lang() == 'query' then
diff --git a/runtime/lua/vim/treesitter/dev.lua b/runtime/lua/vim/treesitter/dev.lua
index 2a6e166ef1..dbf0e73250 100644
--- a/runtime/lua/vim/treesitter/dev.lua
+++ b/runtime/lua/vim/treesitter/dev.lua
@@ -76,9 +76,14 @@ end
 ---
 ---@package
 function TSTreeView:new(bufnr, lang)
-  local parser = vim.treesitter._get_parser(bufnr or 0, lang)
+  local parser = vim.treesitter.get_parser(bufnr or 0, lang, { error = false })
   if not parser then
-    return nil, 'No parser available for the given buffer.'
+    return nil,
+      string.format(
+        'Failed to create TSTreeView for buffer %s: no parser for lang "%s"',
+        bufnr,
+        lang
+      )
   end
 
   -- For each child tree (injected language), find the root of the tree and locate the node within
@@ -539,7 +544,7 @@ local edit_ns = api.nvim_create_namespace('treesitter/dev-edit')
 local function update_editor_highlights(query_win, base_win, lang)
   local base_buf = api.nvim_win_get_buf(base_win)
   local query_buf = api.nvim_win_get_buf(query_win)
-  local parser = assert(vim.treesitter._get_parser(base_buf, lang))
+  local parser = assert(vim.treesitter.get_parser(base_buf, lang, { error = false }))
   api.nvim_buf_clear_namespace(base_buf, edit_ns, 0, -1)
   local query_content = table.concat(api.nvim_buf_get_lines(query_buf, 0, -1, false), '\n')
 
@@ -596,9 +601,10 @@ function M.edit_query(lang)
   end
   vim.cmd(cmd)
 
-  local parser = vim.treesitter._get_parser(buf, lang)
+  local parser = vim.treesitter.get_parser(buf, lang, { error = false })
   if not parser then
-    return nil, 'No parser available for the given buffer'
+    return nil,
+      string.format('Failed to show query editor for buffer %s: no parser for lang "%s"', buf, lang)
   end
   lang = parser:lang()
 
diff --git a/runtime/lua/vim/treesitter/query.lua b/runtime/lua/vim/treesitter/query.lua
index bd0574b8b7..758c8bb356 100644
--- a/runtime/lua/vim/treesitter/query.lua
+++ b/runtime/lua/vim/treesitter/query.lua
@@ -1028,7 +1028,11 @@ end
 ---
 --- @param lang? string language to open the query editor for. If omitted, inferred from the current buffer's filetype.
 function M.edit(lang)
-  vim.treesitter.dev.edit_query(lang)
+  -- TODO(ribru17): Make edit_query return true upon success so we can just assert here
+  local _, err_msg = vim.treesitter.dev.edit_query(lang)
+  if err_msg then
+    error(err_msg)
+  end
 end
 
 return M
diff --git a/runtime/lua/vim/vimhelp.lua b/runtime/lua/vim/vimhelp.lua
index 01af5425c3..5579cc0174 100644
--- a/runtime/lua/vim/vimhelp.lua
+++ b/runtime/lua/vim/vimhelp.lua
@@ -33,7 +33,7 @@ end
 --- Show a table of contents for the help buffer in a loclist
 function M.show_toc()
   local bufnr = vim.api.nvim_get_current_buf()
-  local parser = assert(vim.treesitter._get_parser(bufnr, 'vimdoc'), 'vimdoc parser not found.')
+  local parser = assert(vim.treesitter.get_parser(bufnr, 'vimdoc', { error = false }))
   local query = vim.treesitter.query.parse(
     parser:lang(),
     [[