[tests] Print Console Errors when browser test fails

[dee077]

Checklist

• I have read the OpenWISP Contributing Guidelines.
• I have manually tested the changes proposed in this pull request.
• I have written new test cases for new code and/or updated existing tests for changes to existing code.
• I have updated the documentation.

Reference to Existing Issue

Closes #352

Description of Changes

• Fix getPresentNodesAndLinksCount to fetch from the Basic usage example in the test render the Basic usage example without console errors
• Print console error if they are found.

[devkapilbansal]

Hi @dee077
From this PR title, it looks like you are just adding logs. Here in the description it is mentioned that you are fixing. Kindly ensure that the title is informative.

Also, if this PR is for a fix, isn't there any issue open? If not, you can create one and link it to the PR

[dee077]

Created an issue and changed the title of this PR

[nemesifier]

@devkapilbansal this PR is a follow up of previous changes and I've been discussing it with @dee077. In these cases creating an issue is not such an important necessity but you are super right in pointing out that we need to be clear when communicating, not only in making sure the title and description of the PR is clear but also state that the need of these changes came up during previous discussions. We can also link the previous issue or PR that this PR is related to. That's totally fine.

This PR is a follow up of #269.

[nemesifier]

Thanks @dee077 👍