fix(runtime)!: move "tohtml" to pack/dist/opt/ #34557

Problem:
The "tohtml" plugin is loaded by default.

Solution:
- Move it to `pack/dist/opt/nvim.tohtml/`, it is an "opt-in" plugin now.
- Document guidelines.
- Also revert the `plugin/` locations of `spellfile.lua` and `net.lua`.
  That idea was not worth the trouble, it will be too much re-education
  for too little gain.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/gen/gen_vimdoc.lua b/src/gen/gen_vimdoc.lua
index 1d426a664b..2db5b85b1d 100755
--- a/src/gen/gen_vimdoc.lua
+++ b/src/gen/gen_vimdoc.lua
@@ -431,7 +431,7 @@ local config = {
     },
     files = {
       'runtime/lua/editorconfig.lua',
-      'runtime/lua/tohtml.lua',
+      'runtime/pack/dist/opt/nvim.tohtml/lua/tohtml.lua',
       'runtime/pack/dist/opt/nvim.undotree/lua/undotree.lua',
       'runtime/pack/dist/opt/nvim.difftool/lua/difftool.lua',
       'runtime/lua/nvim/spellfile.lua',
@@ -793,6 +793,10 @@ local function render_fun(fun, classes, cfg)
     return
   end
 
+  if not fun.name then
+    error(('fun.name is nil, check fn_xform(). fun: %s'):format(vim.inspect(fun)))
+  end
+
   if vim.startswith(fun.name, '_') or fun.name:find('[:.]_') then
     return
   end
@@ -997,6 +1001,10 @@ end
 local function render_section(section, add_header)
   local doc = {} --- @type string[]
 
+  if not section.title then
+    error(('section.title is nil, check section_fmt(). section: %s'):format(vim.inspect(section)))
+  end
+
   if add_header ~= false then
     vim.list_extend(doc, {
       string.rep('=', TEXT_WIDTH),