feat(module:core): 修复项目启动报错

[shuizhongxiong]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd-mobile/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[x] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

npm run start 控制台报错：
error TypeError: Cannot read property 'slice' of undefined

Issue Number: N/A

What is the new behavior?

报错信息小时

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[codecov]

Codecov Report

Merging #792 (d183eba) into master (49a9164) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #792      +/-   ##
==========================================
- Coverage   87.01%   86.99%   -0.02%     
==========================================
  Files         164      164              
  Lines        6645     6645              
  Branches     1109     1109              
==========================================
- Hits         5782     5781       -1     
  Misses        421      421              
- Partials      442      443       +1     

Impacted Files	Coverage Δ
...ts/input-item/custom-input/custom-input.service.ts	83.87% <0.00%> (-3.23%)	⬇️

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