Github user soralee commented on the issue: https://github.com/apache/zeppelin/pull/2194 I checked the similar issue ["TypeError: Cannot read property '1' of undefined" in the bar chart](https://issues.apache.org/jira/browse/ZEPPELIN-2273) we have. This error is occured when changing radio button from `Grouped` to `Stacked` like the following screenshot.  But, Fortunately, there is no problem in this branch so, we can also resolve it with this PR!  
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