Common: Fix fmt msg lost in AppendError().Error()

[gbjk]

Retain the .msg field of a go fmt.Errorf .msg field returned by .Error() when wrapping multiple errors. This fixes a situation where a nested stack of errors would lose formatting information, which is often used to supply identifying context. e.g.

err = fmt.Errorf("%w `%s`: %w", errParsingField, fieldName,
parsingError)
errs = common.AppendError(errs, err)

This isn't really an issue with our implementation; Calling Unwrap() on a fmt.Errorf() which returns a wrapErrors will lose that formatting. Our issue was that we were using just Unwrap() to bind together our chain-of-custody.

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)

How has this been tested

• [x] go test ./... -race
• [x] golangci-lint run

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (08da42d) 35.89% compared to head (ae74d1d) 37.80%. Report is 1 commits behind head on master.

Additional details and impacted files

[](https://app.codecov.io/gh/thrasher-corp/gocryptotrader/pull/1484?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thrasher-corp) ```diff @@ Coverage Diff @@ ## master #1484 +/- ## ========================================== + Coverage 35.89% 37.80% +1.90% ========================================== Files 411 411 Lines 177559 147795 -29764 ========================================== - Hits 63733 55870 -7863 + Misses 106048 84152 -21896 + Partials 7778 7773 -5 ``` | [Files](https://app.codecov.io/gh/thrasher-corp/gocryptotrader/pull/1484?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thrasher-corp) | Coverage Δ | | |---|---|---| | [common/common.go](https://app.codecov.io/gh/thrasher-corp/gocryptotrader/pull/1484?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thrasher-corp#diff-Y29tbW9uL2NvbW1vbi5nbw==) | `94.75% <100.00%> (+1.26%)` | :arrow_up: | ... and [386 files with indirect coverage changes](https://app.codecov.io/gh/thrasher-corp/gocryptotrader/pull/1484/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thrasher-corp)

[gbjk]

Note: This commit is from #1358 and has been reviewed already by everyone