fix(DefaultHTTPErrorHandler): return error message when message is an error

[gnuletik]

The current behavior when returning a go error from a echo handler like this:

return echo.NewHTTPError(status.BadRequest, errors.New("error in httperror"))

Is that echo returns an empty JSON object {}.

See the failing test result, without the fix:

    echo_test.go:1356:
        	Error Trace:	/~/echo/echo_test.go:1356
        	Error:      	Not equal:
        	            	expected: "{\"message\":\"error in httperror\"}\n"
        	            	actual  : "{}\n"

        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -1,2 +1,2 @@
        	            	-{"message":"error in httperror"}
        	            	+{}

        	Test:       	TestDefaultHTTPErrorHandler

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (8e425c0) 92.85% compared to head (e7e0db9) 92.86%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2456   +/-   ##
=======================================
  Coverage   92.85%   92.86%           
=======================================
  Files          39       39           
  Lines        4563     4568    +5     
=======================================
+ Hits         4237     4242    +5     
  Misses        237      237           
  Partials       89       89           

Impacted Files	Coverage Δ
echo.go	95.52% <100.00%> (+0.05%)	⬆️

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[aldas]

LGTM

[aldas]

Thank @gnuletik