[enhance]remove falsy column

[anothertempore]

Remove falsy value in columns, so that we can do expression in the column arrays. For example:

let showId = false

const columns = [
  {
    title: 'Name',
    dataIndex: 'name',
    key: 'name'
  },
  showId && {
    title: 'ID',
    dataIndex: 'id',
    key: 'id'
  }
]

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[codecov]

Codecov Report

Merging #515 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #515   +/-   ##
=======================================
  Coverage   99.86%   99.86%           
=======================================
  Files          25       25           
  Lines         764      764           
  Branches      220      220           
=======================================
  Hits          763      763           
  Misses          1        1           

Impacted Files	Coverage Δ
src/Header/Header.tsx	100.00% <100.00%> (ø)

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