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, 3 insertions, 5 deletions

diff --git a/runtime/doc/api.txt b/runtime/doc/api.txt
index cb3b2a3f77..70fda5ce8a 100644
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@@ -1647,11 +1647,9 @@ nvim_command({command})                                       *nvim_command()*
 
     On execution error: fails with Vimscript error, updates v:errmsg.
 
-    Prefer using |nvim_cmd()| or |nvim_exec2()| over this. To evaluate
-    multiple lines of Vim script or an Ex command directly, use
-    |nvim_exec2()|. To construct an Ex command using a structured format and
-    then execute it, use |nvim_cmd()|. To modify an Ex command before
-    evaluating it, use |nvim_parse_cmd()| in conjunction with |nvim_cmd()|.
+    Prefer |nvim_cmd()| or |nvim_exec2()| instead. To modify an Ex command in
+    a structured way before executing it, modify the result of
+    |nvim_parse_cmd()| then pass it to |nvim_cmd()|.
 
     Parameters: ~
       • {command}  Ex command string