ement-directory-search signals error when no rooms found

### OS/platform

Arch Linux

### Emacs version and provenance

GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.41, cairo version 1.18.0) of 2024-02-28

### Emacs command

/usr/bin/emacs

### Emacs frame type

gui

### Ement package version and provenance

0.15-pre @ efb6005 installed via Elpaca

### Actions taken

`M-x ement-directory-search` `guile`

### Observed results

The following error is signaled:

```
Error running timer ‘plz--respond’: (wrong-type-argument number-or-marker-p nil)
```

### Expected results

An directory buffer displaying something along the lines of "No results for $QUERY" or a more informative user-error.

### Backtrace

```elisp
I trimmed the beginning of the backtrace, but you should be able to get an idea from the following:

-lisp
Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
1+(nil)
(format " %%%s%ss" first-column-align (1+ (cdr (car column-sizes))))
(format (format " %%%s%ss" first-column-align (1+ (cdr (car column-sizes))))
(car (car column-sizes)))
(concat
(format (format " %%%s%ss" first-column-align (1+ (cdr (car column-sizes))))
(car (car column-sizes)))
(let*
((--cl-var-- (cdr column-sizes)) (size nil) (name nil) (column-alist nil)
(align nil) (spec nil) (--cl-var-- "") (--cl-var-- t))
(while (consp --cl-var--)
(progn
(setq size (car --cl-var--))
(setq name (car-safe (prog1 size (setq size ...)))))
(setq column-alist (alist-get name formatters nil nil #'equal))
(setq align
(let* ((val (alist-get ... column-alist)))
(cond ((memq val ...) (let nil "-")) ((eq val ...) (let nil ""))
(t (let ... ...)))))
(setq spec (format " %%%s%ss" align size))
(setq --cl-var-- (concat --cl-var-- (format spec name)))
(setq --cl-var-- (cdr --cl-var--)) (setq --cl-var-- nil))
--cl-var--))
(let* ((first-column-name (car (car column-sizes))) (first-column-alist (alist-get first-column-name formatters nil nil #'equal)) (first-column-align (let* ((val (alist-get 'align first-column-alist))) (cond ((memq val '...) (let nil "-")) ((eq val 'right) (let nil "")) (t (let (...) (error "No clause matching `%S'" x374))))))) (concat (format (format " %%%s%ss" first-column-align (1+ (cdr (car column-sizes)))) (car (car column-sizes))) (let* ((--cl-var-- (cdr column-sizes)) (size nil) (name nil) (column-alist nil) (align nil) (spec nil) (--cl-var-- "") (--cl-var-- t)) (while (consp --cl-var--) (progn (setq size (car --cl-var--)) (setq name (car-safe (prog1 size ...)))) (setq column-alist (alist-get name formatters nil nil #'equal)) (setq align (let* ((val ...)) (cond (... ...) (... ...) (t ...)))) (setq spec (format " %%%s%ss" align size)) (setq --cl-var-- (concat --cl-var-- (format spec name))) (setq --cl-var-- (cdr --cl-var--)) (setq --cl-var-- nil)) --cl-var--)))
taxy-magit-section-format-header(nil
(("ID" (align) (formatter . ement-directory-column-format-id))
("Topic" (align) (formatter . ement-directory-column-format-topic))
("Size" (align . right) (formatter . ement-directory-column-format-size))
("Alias" (align) (formatter . ement-directory-column-format-alias))
("Name" (align) (formatter . ement-directory-column-format-name))
(#("✓" 0 1 (help-echo "Joined")) (align)
(formatter . ement-directory-column-format-✓))))
ement-directory--view([] :append-p nil :buffer-name
"*Ement Directory: \"ijustmadethisup\" on matrix.org*" :root-section-name
"Ement Directory: \"ijustmadethisup\" on matrix.org" :init-fn
#f(compiled-function () #))
```

### Etc.

_No response_