Copyparty does not load image while thumbnails are loading.

### Describe the bug
a description of what the bug is

When you open a folder in grid mode with high number of image files, when the thumbnails are loading then if you try to open a image it just stuck. Even if you try to navigate to another folder while thumbnails are loading sometimes that also get stuck but not always.

### To Reproduce
List of steps to reproduce the issue, or, if it's hard to reproduce, then at least a detailed explanation of what you did to run into it

Have a folder with high number of images and open it in grid mode then while thubnails are loading, try to click on one image.

### Expected behavior
a description of what you expected to happen

File should open even though thumbnails are loading.

### Screenshots
if applicable, add screenshots to help explain your problem, such as the kickass crashpage :^)

```
1765946040.7130365

# MainThread (7ea8114a9080)
File: "", line 1, in
File: "python3.12/multiprocessing/spawn.py", line 122, in spawn_main
exitcode = _main(fd, parent_sentinel)
File: "python3.12/multiprocessing/spawn.py", line 135, in _main
return self._bootstrap(parent_sentinel)
File: "python3.12/multiprocessing/process.py", line 314, in _bootstrap
self.run()
File: "python3.12/multiprocessing/process.py", line 108, in run
self._target(*self._args, **self._kwargs)
File: "pe-copyparty.0.1932.0/copyparty/broker_mpw.py", line 56, in __init__
Daemon(self.main, "mpw-main").join()
File: "lib/python3.12/threading.py", line 1147, in join
self._wait_for_tstate_lock()
File: "lib/python3.12/threading.py", line 1167, in _wait_for_tstate_lock
if lock.acquire(block, timeout):

# QueueFeederThread (7ea7e2ffd6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "lib/python3.12/threading.py", line 1010, in run
self._target(*self._args, **self._kwargs)
File: "python3.12/multiprocessing/queues.py", line 251, in _feed
nwait()
File: "lib/python3.12/threading.py", line 365, in wait
if not gotit:

# hsrv-pt-5 (7ea7e37fe6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 257, in periodic
time.sleep(2 if self.tp_ncli or self.ncli else 10)

# httpconn-0.16-60231 (7ea7c3fff6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 472, in thr_poolw
self.thr_client(sck, addr)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 518, in thr_client
cli.run()
File: "pe-copyparty.0.1932.0/copyparty/httpconn.py", line 209, in run
if not self.cli.run():
File: "pe-copyparty.0.1932.0/copyparty/httpcli.py", line 780, in run
return self.handle_get() and self.keepalive
File: "pe-copyparty.0.1932.0/copyparty/httpcli.py", line 1375, in handle_get
return self.tx_stack()
File: "pe-copyparty.0.1932.0/copyparty/httpcli.py", line 5451, in tx_stack
ret = html_escape(alltrace(self.args.stack_v))
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 1437, in alltrace
for fn, lno, name, line in traceback.extract_stack(stack):

# httpsrv-n5-listen-0.0.0.0-3923 (7ea7e1ffb6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 385, in thr_listen
sck, saddr = srv_sck.accept()
File: "lib/python3.12/socket.py", line 295, in accept
fd, addr = self._accept()

# mpw-main (7ea7e27fc6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/broker_mpw.py", line 73, in main
retq_id, dest, args = self.q_pend.get()
File: "python3.12/multiprocessing/queues.py", line 103, in get
res = self._recv_bytes()
File: "python3.12/multiprocessing/connection.py", line 216, in recv_bytes
buf = self._recv_bytes(maxlength)
File: "python3.12/multiprocessing/connection.py", line 430, in _recv_bytes
buf = self._recv(4)
File: "python3.12/multiprocessing/connection.py", line 395, in _recv
chunk = read(handle, remaining)

# hsrv-n5-i2da5-poolw (7ea7c17fa6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 461, in thr_poolw
task = self.tp_q.get()
File: "lib/python3.12/queue.py", line 171, in get
self.not_empty.wait()
File: "lib/python3.12/threading.py", line 355, in wait
waiter.acquire()

# hsrv-n5-i2da5-poolw (7ea7c1ffb6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 461, in thr_poolw
task = self.tp_q.get()
File: "lib/python3.12/queue.py", line 171, in get
self.not_empty.wait()
File: "lib/python3.12/threading.py", line 355, in wait
waiter.acquire()

# hsrv-n5-i2da5-poolw (7ea7c27fc6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 461, in thr_poolw
task = self.tp_q.get()
File: "lib/python3.12/queue.py", line 171, in get
self.not_empty.wait()
File: "lib/python3.12/threading.py", line 355, in wait
waiter.acquire()

# hsrv-n5-i2da5-poolw (7ea7c2ffd6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 461, in thr_poolw
task = self.tp_q.get()
File: "lib/python3.12/queue.py", line 171, in get
self.not_empty.wait()
File: "lib/python3.12/threading.py", line 355, in wait
waiter.acquire()

# hsrv-n5-i2da5-poolw (7ea7c37fe6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 461, in thr_poolw
task = self.tp_q.get()
File: "lib/python3.12/queue.py", line 171, in get
self.not_empty.wait()
File: "lib/python3.12/threading.py", line 355, in wait
waiter.acquire()

# hsrv-n5-i2da5-poolw (7ea7e0ff96c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 461, in thr_poolw
task = self.tp_q.get()
File: "lib/python3.12/queue.py", line 171, in get
self.not_empty.wait()
File: "lib/python3.12/threading.py", line 355, in wait
waiter.acquire()

# hsrv-n5-i2da5-poolw (7ea7f1eff6c0)
File: "lib/python3.12/threading.py", line 1030, in _bootstrap
self._bootstrap_inner()
File: "lib/python3.12/threading.py", line 1073, in _bootstrap_inner
self.run()
File: "pe-copyparty.0.1932.0/copyparty/util.py", line 733, in run
self.fun(*self.a, **self.ka)
File: "pe-copyparty.0.1932.0/copyparty/httpsrv.py", line 461, in thr_poolw
task = self.tp_q.get()
File: "lib/python3.12/queue.py", line 171, in get
self.not_empty.wait()
File: "lib/python3.12/threading.py", line 355, in wait
waiter.acquire()

```

### Server details (if you are using docker/podman)
remove the ones that are not relevant:
* **server OS / version:**
* **how you're running copyparty:** (docker/podman/something-else)
* **docker image:** (variant, version, and arch if you know)
* **copyparty arguments and/or config-file:**

### Server details (if you're NOT using docker/podman)
remove the ones that are not relevant:
* **server OS / version:** Ubuntu 24.04
* **what copyparty did you grab:** (sfx/exe/pip/arch/...) sfx
* **how you're running it:** (in a terminal, as a systemd-service, ...) systemd-service
* run copyparty with `--version` and grab the last 3 lines (they start with `copyparty`, `CPython`, `sqlite`) and paste them below this line:
* copyparty v1.19.22 "usernames" (2025-12-14)
CPython v3.12.3 on Linux64 24.04.1 [GCC 13.3.0]
sqlite 3.45.1*1 | jinja 3.1.6 | pyftpd 1.5.10 | tftp 0.4.0

* **copyparty arguments and/or config-file:**

### Client details
if the issue is possibly on the client-side, then mention some of the following:
* the device type and model:
* OS version:
* browser version:

### The rest of the stack
if you are connecting directly to copyparty then that's cool, otherwise please mention everything else between copyparty and the browser (reverseproxy, tunnels, etc.)

### Server log
if the issue might be server-related, include everything that appears in the copyparty log during startup, and also anything else you think might be relevant

### Additional context
any other context about the problem here

2025-12-16 23:11:23.636 dependencies found: sqlite (sessions and file/media indexing)
2025-12-16 23:11:23.636 dependencies found: pillow (image thumbnails (plenty fast))
2025-12-16 23:11:23.636 dependencies found: vips (image thumbnails (faster, eats more ram))
2025-12-16 23:11:23.636 dependencies found: pillow-webp (create thumbnails as webp files)
2025-12-16 23:11:23.636 dependencies found: ffmpeg (transcode audio, create spectrograms, video thumbnails, good-but-slow image thumbnails)
2025-12-16 23:11:23.636 dependencies found: ffprobe (transcode audio, create spectrograms, video thumbnails, read audio/media tags)
2025-12-16 23:11:23.636 dependencies found: mutagen (read audio tags (ffprobe is better but slower))
2025-12-16 23:11:23.636 dependencies found: argon2 (secure password hashing (advanced users only))
2025-12-16 23:11:23.636 dependencies found: pyzmq (send zeromq messages from event-hooks)
2025-12-16 23:11:23.636 dependencies found: pillow-heif (read .heif images with pillow (rarely useful))
2025-12-16 23:11:23.636 dependencies found: pillow-avif (read .avif images with pillow (rarely useful))
2025-12-16 23:11:23.636 dependencies found: rawpy (read RAW images)