console error info not friendly

## Issue Description
When I want to create a flow rules, when the dashboard can not connect to the sentinel core, it shows the bellow result
Type: *bug report* or *feature request*

### Describe what happened (or what feature you want)


### Describe what you expected to happen

### How to reproduce it (as minimally and precisely as possible)

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### Tell us your environment

### Anything else we need to know?

Start by reproducing the dashboard flow-rule creation attempt while the dashboard cannot connect to the Sentinel core, then inspect the resulting console error shown in the attached image. Done would mean replacing the current error information with a clearer message, but the issue does not name files, tests, or a precise expected wording.

Written by the indexing model from the issue text.