Fix panic caused by unwrap

[cardigan1008]

Fix 8.Unwrap error in #244

In the replay file, from_format_str takes "%" as format_str, thus causing the format returned by from_str empty.

hifitime/src/efmt/format.rs

Line 159 in 822c0a0

let mut cur_item = self.items[cur_item_idx].unwrap();

This results in the items in parse being empty, which causes an unwrap error. In my opinion, it should be classified as an UnknownFormat error since it's related to format.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 81.66%. Comparing base (822c0a0) to head (b8e3a17).

Files	Patch %	Lines
src/efmt/format.rs	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #285      +/-   ##
==========================================
- Coverage   81.67%   81.66%   -0.02%     
==========================================
  Files          16       16              
  Lines        3836     3839       +3     
==========================================
+ Hits         3133     3135       +2     
- Misses        703      704       +1     

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[ChristopherRabotin]

Thanks for your contributions, Yunbo, I finally fixed the CI pipelines, so I've merged all of your outstanding PRs.

[cardigan1008]

Thanks for your contributions, Yunbo, I finally fixed the CI pipelines, so I've merged all of your outstanding PRs.

Thanks for your reviews too! They're a lot of help to the panic repair tool I've been working on.