Fix legend on cases/day graph

[Utwo]

Closes #361

[vercel]

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[web-sys1]

Sorry @catileptic, but the problem is far to be resolved.

Also, got error message when I've opened DevTools > Console in Chrome browser:

TypeError: Cannot read property 'seriesName' of undefined
    at formatter (main.845387c9.chunk.js?__WB_REVISION__=eb503ea4e7511eb64dcc:1)
    at n._showTooltipContent (TooltipView.js:543)
    at n.<anonymous> (TooltipView.js:437)
    at util.js:426
    at n._showOrMove (TooltipView.js:355)
    at n._showAxisTooltip (TooltipView.js:433)
    at n._tryShow (TooltipView.js:330)
    at n.manuallyShowTip (TooltipView.js:229)
    at c (echarts.js:1039)
    at V.<anonymous> (echarts.js:1034)

[Utwo]

Sorry @catileptic, but the problem is far to be resolved.

Also, got error message when I've opened DevTools > Console in Chrome browser:

TypeError: Cannot read property 'seriesName' of undefined
    at formatter (main.845387c9.chunk.js?__WB_REVISION__=eb503ea4e7511eb64dcc:1)
    at n._showTooltipContent (TooltipView.js:543)
    at n.<anonymous> (TooltipView.js:437)
    at util.js:426
    at n._showOrMove (TooltipView.js:355)
    at n._showAxisTooltip (TooltipView.js:433)
    at n._tryShow (TooltipView.js:330)
    at n.manuallyShowTip (TooltipView.js:229)
    at c (echarts.js:1039)
    at V.<anonymous> (echarts.js:1034)

Hello, please test the following URL: https://date-la-zi-git-fork-utwo-fix-case-day-legend.code4romania.vercel.app/

[surdu]

@web-sys1 the fix is not published yet.

[web-sys1]

@surdu Worked well. It takes a while to be published on website.

[web-sys1]

Also, I requested adding processed tests graph (see #349)