do not check sub-modes in get_tags_at

cull test-dependency

lua/u/renderer.lua

@@ -340,7 +340,9 @@ function Renderer:_expr_map_callback(mode, lhs) -- {{{
   -- find the tag with the smallest intersection that contains the cursor:
   local pos0 = vim.api.nvim_win_get_cursor(0)
   pos0[1] = pos0[1] - 1 -- make it actually 0-based
+  log('_expr_map_callback: pos0:', pos0)
   local pos_infos = self:get_tags_at(pos0)
+  log('_expr_map_callback: pos_infos:', pos_infos)
 
   if #pos_infos == 0 then return lhs end
 
@@ -538,21 +540,26 @@ end -- }}}
 function Renderer:get_tags_at(pos0, mode) -- {{{
   local cursor_line0, cursor_col0 = pos0[1], pos0[2]
   if not mode then mode = vim.api.nvim_get_mode().mode end
+  mode = mode:sub(1, 1) -- we don't care about sub-modes
+
+  local raw_overlapping_extmarks = vim.api.nvim_buf_get_extmarks(
+    self.bufnr,
+    self.ns,
+    pos0,
+    pos0,
+    { details = true, overlap = true }
+  )
+  log(
+    'get_tags_at: context:',
+    { pos0 = pos0, mode = mode, raw_overlapping_extmarks = raw_overlapping_extmarks }
+  )
 
   -- The cursor (block) occupies **two** extmark spaces: one for it's left
   -- edge, and one for it's right. We need to do our own intersection test,
   -- because the NeoVim API is over-inclusive in what it returns:
   --- @type u.renderer.RendererExtmark[]
   local mapped_extmarks = vim
-    .iter(
-      vim.api.nvim_buf_get_extmarks(
-        self.bufnr,
-        self.ns,
-        pos0,
-        pos0,
-        { details = true, overlap = true }
-      )
-    )
+    .iter(raw_overlapping_extmarks)
     --- @return u.renderer.RendererExtmark
     :map(function(ext)
       --- @type number, number, number, { end_row?: number; end_col?: number }|nil