Unhandled exception: RuntimeError: dictionary changed size during iteration

### Step 1: Please describe your environment

* ZeroNet version: _____
* Operating system: _____
* Web browser: _____
* Tor status: not available/always/disabled
* Opened port: yes/no
* Special configuration: ____

### Step 2: Describe the problem:

#### Steps to reproduce:

1. _____
2. _____
3. _____

#### Observed Results:

* What happened? This could be a screenshot, a description, log output (you can send log/debug.log file to hello@zeronet.io if necessary), etc.

#### Expected Results:

* What did you expect to happen?

No source file, test, environment details, reproduction steps, or traceback are provided. Start by collecting the missing environment and reproduction information, then use the full RuntimeError traceback to locate the affected dictionary iteration. Done means reproducing the exception and confirming it no longer occurs under the reported conditions.

索引モデルが issue の本文から書いたものです。