Check if c3 artifact exists before load

[SebouChu]

What does this PR do? How does it affect users?

When a chart is hidden at first, there's a callback which loads the dataset matrix in it. This PR adds a condition to check if datavizInstance.view._artifacts.c3 exists before calling the load function on it.

Related tickets?

I didn't create a ticket for this, but I had a problem with using this library and Keen Analysis.

Loading the results from a Keen Analysis query in a closed tab and then accessing it showed an error in the inspector : Uncaught TypeError: Cannot read property 'load' of undefined.

How should this be tested?

Load a page containing a chart with results loaded from a Keen Analysis query in a closed tab, then access it to see the chart.

Fetch the branch and/or deploy to staging to test the following:

• [ ] Does the code compile without warnings (check shell, console)?
• [ ] Do all tests pass?
• [ ] Does the UI, pixel by pixel, look exactly as expected (check various screen sizes, including mobile)?
• [ ] If the feature makes requests from the browser, inspect them in the Web Inspector. Do they look as expected (parameters, headers, etc)?
• [ ] If the feature sends data to Keen, is the data visible in the project if you run an extraction (include link to collection/query)?
• [ ] If the feature saves data to a database, can you confirm the data is indeed created in the database?

[apryka]

the fix has been released in v3.14.2

@SebouChu thanks for finding!

[SebouChu]

@apryka Thanks for merging & releasing that fast! Have a good day!