[bugfix] Tab: may cause error when render title slot

[chenjiahan]

No description provided.

[codecov-io]

Codecov Report

Merging #3631 into dev will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##              dev    #3631      +/-   ##
==========================================
+ Coverage   92.87%   92.87%   +<.01%     
==========================================
  Files         119      119              
  Lines        2611     2612       +1     
  Branches      226      226              
==========================================
+ Hits         2425     2426       +1     
  Misses        161      161              
  Partials       25       25

Impacted Files	Coverage Δ
packages/tabs/index.js	91.2% <100%> (+0.07%)	⬆️

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