Broken stack (with "1 instruction trace errors" warning) on non-tailrecursive code

For example, running `magic-trace run -full-execution` on this code:

```ocaml
let rec go dir =
if (Unix.lstat dir).st_kind = Unix.S_DIR then
let rec handle_dir d =
match Unix.readdir d with
| exception End_of_file -> Unix.closedir d; ()
| "." | ".." -> handle_dir d
| subdir -> go (Filename.concat dir subdir); handle_dir d
in
handle_dir (Unix.opendir dir)
else
()

(* a large directory structure, for example the ocaml source code checked out via git *)
let dir = "repositories/ocaml"
let () = ignore (go dir)
```

Prints `Warning: 1 instruction trace errors` and shows a cut-off stack as shown below (if a bigger directory is chosen, it happens more than once):


The issue happens in similar code that doesn't use exceptions, so I don't think irregular control flow is the issue. Just for reference, this is in a 4.14 flambda switch and the executable is built with `dune --profile=release`.

Reproduce the warning with the provided OCaml example using `magic-trace run -full-execution`, comparing a small directory with a large one. Investigate how the trace is collected and rendered for non-tailrecursive calls; done means the complete stack is shown without an instruction trace error.

Written by the indexing model from the issue text.