fixed 'bad access: nil dereference' when calling Error() method if it…

[henng]

SEE #576

[codecov]

Codecov Report

Merging #577 into master will decrease coverage by 0.01%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master     #577      +/-   ##
==========================================
- Coverage   71.82%   71.81%   -0.02%     
==========================================
  Files          32       32              
  Lines        7834     7838       +4     
==========================================
+ Hits         5627     5629       +2     
- Misses       1676     1677       +1     
- Partials      531      532       +1

Impacted Files	Coverage Δ
terror/terror.go	73.43% <50%> (-0.76%)	⬇️
ast/functions.go	76.74% <0%> (ø)	⬆️

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[kennytm]

why e == nil is not enough? *Error is a concrete type unlike interface{}.

[henng]

you are right, e == nil is better.

[kennytm]

(ditto)

[jyno12]

这个现在有啥别的修改？model/ddl中的job也遇到这个问题。

import (
	"github.com/pingcap/parser/model"
	"testing"
)

func TestJob(t *testing.T) {
	j:=model.Job{}
	t.Logf("%v",j)
}

由于job中的error为nil也是这个问题。

[tiancaiamao]

Ping @henng ?

[ti-chi-bot]

@henng: PR needs rebase.

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.81%. Comparing base (aa72817) to head (081dece).
⚠️ Report is 421 commits behind head on master.

⚠️ Current head 081dece differs from pull request most recent head 4a34588

Please upload reports for the commit 4a34588 to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #577      +/-   ##
==========================================
- Coverage   71.82%   71.81%   -0.02%     
==========================================
  Files          32       32              
  Lines        7834     7838       +4     
==========================================
+ Hits         5627     5629       +2     
- Misses       1676     1677       +1     
- Partials      531      532       +1     

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