fix(api): generic error messages, not using TRY_WRAP #31596

Problem:
- API functions using `try_start` directly, do not surface the
  underlying error message, and instead show generic messages.
- Error-handling code is duplicated in the API impl.
- Failure modes are not tested.

Solution:
- Use `TRY_WRAP`.
- Add tests.

1 files changed, 21 insertions, 1 deletions

diff --git a/test/functional/api/vim_spec.lua b/test/functional/api/vim_spec.lua
index 2eeb5c18a1..879df690d1 100644
--- a/test/functional/api/vim_spec.lua
+++ b/test/functional/api/vim_spec.lua
@@ -695,7 +695,7 @@ describe('API', function()
         pcall_err(request, 'nvim_call_dict_function', 42, 'f', { 1, 2 })
       )
       eq(
-        'Failed to evaluate dict expression',
+        'Vim:E121: Undefined variable: foo',
         pcall_err(request, 'nvim_call_dict_function', 'foo', 'f', { 1, 2 })
       )
       eq('dict not found', pcall_err(request, 'nvim_call_dict_function', '42', 'f', { 1, 2 }))
@@ -1957,6 +1957,16 @@ describe('API', function()
       api.nvim_set_current_win(api.nvim_list_wins()[2])
       eq(api.nvim_list_wins()[2], api.nvim_get_current_win())
     end)
+
+    it('failure modes', function()
+      n.command('split')
+
+      eq('Invalid window id: 9999', pcall_err(api.nvim_set_current_win, 9999))
+
+      -- XXX: force nvim_set_current_win to fail somehow.
+      n.command("au WinLeave * throw 'foo'")
+      eq('WinLeave Autocommands for "*": foo', pcall_err(api.nvim_set_current_win, 1000))
+    end)
   end)
 
   describe('nvim_{get,set}_current_tabpage, nvim_list_tabpages', function()
@@ -1976,6 +1986,16 @@ describe('API', function()
       eq(api.nvim_list_tabpages()[2], api.nvim_get_current_tabpage())
       eq(api.nvim_list_wins()[2], api.nvim_get_current_win())
     end)
+
+    it('failure modes', function()
+      n.command('tabnew')
+
+      eq('Invalid tabpage id: 999', pcall_err(api.nvim_set_current_tabpage, 999))
+
+      -- XXX: force nvim_set_current_tabpage to fail somehow.
+      n.command("au TabLeave * throw 'foo'")
+      eq('TabLeave Autocommands for "*": foo', pcall_err(api.nvim_set_current_tabpage, 1))
+    end)
   end)
 
   describe('nvim_get_mode', function()