Fixing invalid X-MiniProfiler-Ids responses

Sometimes the X-MiniProfiler-Ids response contains a double-array instead of a single.
With this change, we take the first one and discard the rest.

A normal response looks like that:
```json
["94A4A68F-C2C5-4A66-8369-CC5DAAEF3640"]
```
Sometimes I get this response:
```json
["94A4A68F-C2C5-4A66-8369-CC5DAAEF3640"], ["94A4A68F-C2C5-4A66-8369-CC5DAAEF3640"]
```
I do not know why, but this is a fix/workaround for that.