fix(priority): don't insert an empty [# ] cookie when clearing priority

lua/orgmode/files/headline.lua

@@ -347,9 +347,17 @@ end
 ---@param priority string
 function Headline:set_priority(priority)
   local _, priority_node = self:get_priority()
+  priority = vim.trim(priority)
+
+  if priority == '' then
+    if priority_node then
+      return self:_set_node_text(priority_node, '')
+    end
+    return
+  end
+
   if priority_node then
-    local text = (vim.trim(priority) == '') and '' or ('[#%s]'):format(priority)
-    return self:_set_node_text(priority_node, text)
+    return self:_set_node_text(priority_node, ('[#%s]'):format(priority))
   end
 
   local todo, todo_node = self:get_todo()

tests/plenary/ui/mappings/priority_spec.lua

@@ -62,6 +62,17 @@ describe('Priority mappings', function()
     assert.are.same('* TODO Test orgmode', vim.fn.getline(1))
   end)
 
+  it('should do nothing if <Space> is pressed on a line without a priority', function()
+    alpha_config()
+    helpers.create_file({
+      '* TODO Test orgmode',
+    })
+    vim.fn.cursor(1, 1)
+    assert.are.same('* TODO Test orgmode', vim.fn.getline(1))
+    vim.cmd('norm ,o, \r')
+    assert.are.same('* TODO Test orgmode', vim.fn.getline(1))
+  end)
+
   it('should add a priority if the item does not already have one', function()
     helpers.create_file({
       '* TODO Test orgmode',