[Improvement] Throw IllegalArgumentException if parse time placeholder error

[ruanwenjun]

Purpose of the pull request

Avoid throw NPE or some other unreadable Exception.

Brief change log

Verify this pull request

This pull request is code cleanup without any test coverage.

(or)

This pull request is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(or)

If your pull request contain incompatible change, you should also add it to docs/docs/en/guide/upgrede/incompatible.md

[codecov-commenter]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (308e4fb) 38.01% compared to head (368a023) 38.02%.

❗ Current head 368a023 differs from pull request most recent head 26544c7. Consider uploading reports for the commit 26544c7 to get more accurate results

Files	Patch %	Lines
...r/plugin/task/api/parser/TimePlaceholderUtils.java	50.00%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##                dev   #15514   +/-   ##
=========================================
  Coverage     38.01%   38.02%           
- Complexity     4692     4693    +1     
=========================================
  Files          1304     1304           
  Lines         44814    44812    -2     
  Branches       4804     4804           
=========================================
+ Hits          17038    17040    +2     
+ Misses        25924    25921    -3     
+ Partials       1852     1851    -1     

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[sonarcloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

17 New issues
0 Security Hotspots
64.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[rickchengx]

LGTM