[bugfix] IS NOT NULL filter triggers KeyError: 'val' (#5764)
[bugfix] IS NOT NULL filter triggers KeyError: 'val' (#5764)


zhouyao1994/incubator-superset,apache/incubator-superset,zhouyao1994/incubator-superset,apache/incubator-superset,airbnb/caravel,zhouyao1994/incubator-superset,airbnb/superset,airbnb/caravel,airbnb/superset,apache/incubator-superset,mistercrunch/panoramix,apache/incubator-superset,airbnb/superset,airbnb/caravel,mistercrunch/panoramix,zhouyao1994/incubator-superset,mistercrunch/panoramix,mistercrunch/panoramix,airbnb/caravel,airbnb/superset,apache/incubator-superset,zhouyao1994/incubator-superset