Problem with line chart

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USER STORY

Sometimes there are tags in duplicate.
More importantly, there is sometime this error :
TypeError: Cannot read property 'destroy' of null
When chart js try to destroy the chart.

ACCEPTANCE CRITERIA

DEFINITION OF DONE

• Code builds without warnings (technical task)
• Code unit tested (technical task)
• Code is reviewed by a peer colleague
• Documentation updated (user story)
• Build pushed to demo server (user story)