测试unity webGL项目

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**Describe the bug**
在测试unity webGL项目的时候，网页已经打开，使用 图像识别是否存在，出现了一个不理解的错误。

```
paste traceback here
```

**To Reproduce**
Steps to reproduce the behaviour:
1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

**Expected behaviour**
A clear and concise description of what you expected to happen.

**Screenshots**

**python version:** `python3.6.5`

**poco version:** `1.0.69`
> You can get poco version via `pip freeze` command.

**Smartphone (please complete the following information):**
- Device: [e.g. google pixel 2]

- more information if have

**Additional context**
Add any other context about the problem here.