error_message: more friendly error message #711

[GMHDBJD]

manually cherrypick #771

What problem does this PR solve?

• use TError to replace ProcessError

   "errors": [
                            {
                                "msg": "",
                                "error": {
                                    "ErrCode": 10006,
                                    "ErrClass": 1,
                                    "ErrScope": 2,
                                    "ErrLevel": 3,
                                    "Message": "this is the error message",
                                    "RawCause": "this is the raw cause",
                                    "Workaround": "this is the workaround"
                                }
                            }
           ]
  

  will become

  "errors": [
                            {
                                "ErrCode": 10006,
                                "ErrClass": "database",
                                "ErrScope": "downstream",
                                "ErrLevel": "high",
                                "Message": "this is the error message",
                                "RawCause": "this is the raw cause",
                                "Workaround": "this is the workaround"
                            }
          ]
  

• only show error message, rawcause, workaround which is not nil

  [code=10001:class=database:scope=not-set:level=high], Message: database driver error, RawCause: 'tidb_retry_limit' can't be set to the value, Workaround: Please check your database config
  

  [code=48001:class=not-set:scope=not-set:level=high]
  

What is changed and how it works?

• update ProcessError proto
• add ErrNotSet, use for unknow error
• better error message format

[codecov]

Codecov Report

Merging #799 into release-1.0 will increase coverage by 0.5657%.
The diff coverage is 63.1424%.

@@                 Coverage Diff                 @@
##           release-1.0       #799        +/-   ##
===================================================
+ Coverage      57.2665%   57.8323%   +0.5657%     
===================================================
  Files              161        167         +6     
  Lines            16741      16617       -124     
===================================================
+ Hits              9587       9610        +23     
+ Misses            6206       6132        -74     
+ Partials           948        875        -73     

[lance6716]

LGTM

[ti-srebot]

@lance6716, Thanks for your review, however we are sorry that your vote won't be count. You are not a reviewer or committer or co-leader or leader for the related sigs:tools(slack).

[WangXiangUSTC]

please solve the conflicts

[WangXiangUSTC]

LGTM