fix cannot show error message when fail to rebuild

[nexustar]

What problem does this PR solve?

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

[codecov-commenter]

Codecov Report

Patch coverage: 9.09% and project coverage change: -0.05 :warning:

Comparison is base (c0cacb0) 30.11% compared to head (f8e35bf) 30.05%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #444 +/- ## ========================================== - Coverage 30.11% 30.05% -0.05% ========================================== Files 50 50 Lines 4218 4229 +11 ========================================== + Hits 1270 1271 +1 - Misses 2778 2788 +10 Partials 170 170 ``` | Flag | Coverage Δ | | |---|---|---| | unittests | `30.05% <9.09%> (-0.05%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://app.codecov.io/gh/pingcap/diag/pull/444?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap) | Coverage Δ | | |---|---|---| | [pkg/packager/packager.go](https://app.codecov.io/gh/pingcap/diag/pull/444?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap#diff-cGtnL3BhY2thZ2VyL3BhY2thZ2VyLmdv) | `13.88% <0.00%> (-0.20%)` | :arrow_down: | | [pkg/utils/utils.go](https://app.codecov.io/gh/pingcap/diag/pull/444?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap#diff-cGtnL3V0aWxzL3V0aWxzLmdv) | `0.00% <0.00%> (ø)` | | | [cmd/diag/command/util\_metricdump.go](https://app.codecov.io/gh/pingcap/diag/pull/444?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pingcap#diff-Y21kL2RpYWcvY29tbWFuZC91dGlsX21ldHJpY2R1bXAuZ28=) | `37.14% <100.00%> (+0.60%)` | :arrow_up: |

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