OPAL-1974: Show "no summary data available" on continuous variable summary when N is 0
Merge pull request #265 from emorency/feature/OPAL-1974-empty-summary-charts

OPAL-1974: Show "no summary data available" on continuous variable summa...
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Category edition prototyped
Magma layout reviewed
JVM View layout reviewed
Projects layout reviewed
Categorical summary layout
Magma widget heading