message: [bugfix] IS NOT NULL filter triggers KeyError: 'val'
diff: @@ -724,13 +724,13 @@ def to_adhoc(filt, expressionType='SIMPLE', clause='where'):
  if expressionType == 'SIMPLE':
  result.update({
  - 'comparator': filt['val'],
  - 'operator': filt['op'],
  - 'subject': filt['col'],
  + 'comparator': filt.get('val'),
  + 'operator': filt.get('op'),
  + 'subject': filt.get('col'),
  })
  elif expressionType == 'SQL':
  result.update({
  - 'sqlExpression': filt[clause],
  + 'sqlExpression': filt.get(clause),
  })
  return result
  