[explore v2] fix explorev2 chart errors

[ascott]

• only show line chart if viz type is line
• fix proptype validations

@vera-liu

[vera-liu]

thanks for the quick fix! 👍

[ascott]

i'm not sure this will work.

[ascott]

my bad, TIL arrow functions can just return objects:

return this.props.data.map((d) => (
  <V.VictoryLine
    key={d.key}
    data={d.values}
    interpolation="cardinal"
    style={{ data: { stroke: this.keysToColorsMap[d.key] } }}
   />
));