4 files changed, 15 insertions, 3 deletions
diff --git a/runtime/lua/vim/filetype.lua b/runtime/lua/vim/filetype.lua
index 256c053801..8911eafc71 100644
--- a/runtime/lua/vim/filetype.lua
+++ b/runtime/lua/vim/filetype.lua
@@ -156,6 +156,7 @@ local extension = {
   bas = function(path, bufnr)
     return require('vim.filetype.detect').bas(bufnr)
   end,
+  bass = 'bass',
   bi = function(path, bufnr)
     return require('vim.filetype.detect').bas(bufnr)
   end,
diff --git a/runtime/lua/vim/treesitter.lua b/runtime/lua/vim/treesitter.lua
index b2909f2154..b63247aa2c 100644
--- a/runtime/lua/vim/treesitter.lua
+++ b/runtime/lua/vim/treesitter.lua
@@ -47,7 +47,8 @@ function M._create_parser(bufnr, lang, opts)
 
   vim.fn.bufload(bufnr)
 
-  language.add(lang, { filetype = vim.bo[bufnr].filetype })
+  local ft = vim.bo[bufnr].filetype
+  language.add(lang, { filetype = ft ~= '' and ft or nil })
 
   local self = LanguageTree.new(bufnr, lang, opts)
 
diff --git a/runtime/lua/vim/treesitter/_range.lua b/runtime/lua/vim/treesitter/_range.lua
index b87542c20f..8decd3a1fd 100644
--- a/runtime/lua/vim/treesitter/_range.lua
+++ b/runtime/lua/vim/treesitter/_range.lua
@@ -61,7 +61,7 @@ function M.intercepts(r1, r2)
   local off_1 = #r1 == 6 and 1 or 0
   local off_2 = #r1 == 6 and 1 or 0
 
-  local srow_1, scol_1, erow_1, ecol_1 = r1[1], r2[2], r1[3 + off_1], r1[4 + off_1]
+  local srow_1, scol_1, erow_1, ecol_1 = r1[1], r1[2], r1[3 + off_1], r1[4 + off_1]
   local srow_2, scol_2, erow_2, ecol_2 = r2[1], r2[2], r2[3 + off_2], r2[4 + off_2]
 
   -- r1 is above r2
@@ -85,7 +85,7 @@ function M.contains(r1, r2)
   local off_1 = #r1 == 6 and 1 or 0
   local off_2 = #r1 == 6 and 1 or 0
 
-  local srow_1, scol_1, erow_1, ecol_1 = r1[1], r2[2], r1[3 + off_1], r1[4 + off_1]
+  local srow_1, scol_1, erow_1, ecol_1 = r1[1], r1[2], r1[3 + off_1], r1[4 + off_1]
   local srow_2, scol_2, erow_2, ecol_2 = r2[1], r2[2], r2[3 + off_2], r2[4 + off_2]
 
   -- start doesn't fit
diff --git a/runtime/lua/vim/treesitter/language.lua b/runtime/lua/vim/treesitter/language.lua
index 5bcc786e88..5f34d9cd56 100644
--- a/runtime/lua/vim/treesitter/language.lua
+++ b/runtime/lua/vim/treesitter/language.lua
@@ -60,6 +60,16 @@ function M.add(lang, opts)
     filetype = { filetype, { 'string', 'table' }, true },
   })
 
+  if filetype == '' then
+    error(string.format("'%s' is not a valid filetype", filetype))
+  elseif type(filetype) == 'table' then
+    for _, f in ipairs(filetype) do
+      if f == '' then
+        error(string.format("'%s' is not a valid filetype", filetype))
+      end
+    end
+  end
+
   M.register(lang, filetype or lang)
 
   if vim._ts_has_language(lang) then