Integration with github.com/pkg/errors (#152)

* Squashed changes from #137

* Try to extract pkg/errors cause and use it

client.go

@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"github.com/certifi/gocertifi"
+	pkgErrors "github.com/pkg/errors"
 )
 
 const (
@@ -639,7 +640,9 @@ func (client *Client) CaptureError(err error, tags map[string]string, interfaces
 		return ""
 	}
 
-	packet := NewPacket(err.Error(), append(append(interfaces, client.context.interfaces()...), NewException(err, NewStacktrace(1, 3, client.includePaths)))...)
+	cause := pkgErrors.Cause(err)
+
+	packet := NewPacket(cause.Error(), append(append(interfaces, client.context.interfaces()...), NewException(cause, GetOrNewStacktrace(err, 1, 3, client.includePaths)))...)
 	eventID, _ := client.Capture(packet, tags)
 
 	return eventID

http.go

@@ -73,7 +73,7 @@ func RecoveryHandler(handler func(http.ResponseWriter, *http.Request)) func(http
 			if rval := recover(); rval != nil {
 				debug.PrintStack()
 				rvalStr := fmt.Sprint(rval)
-				packet := NewPacket(rvalStr, NewException(errors.New(rvalStr), NewStacktrace(2, 3, nil)), NewHttp(r))
+				packet := NewPacket(rvalStr, NewException(errors.New(rvalStr), GetOrNewStacktrace(rval.(error), 2, 3, nil)), NewHttp(r))
 				Capture(packet, nil)
 				w.WriteHeader(http.StatusInternalServerError)
 			}

stacktrace.go

@@ -13,6 +13,8 @@ import (
 	"runtime"
 	"strings"
 	"sync"
+
+	"github.com/pkg/errors"
 )
 
 // https://docs.getsentry.com/hosted/clientdev/interfaces/#failure-interfaces
@@ -49,6 +51,35 @@ type StacktraceFrame struct {
 	InApp        bool     `json:"in_app"`
 }
 
+// Try to get stacktrace from err as an interface of github.com/pkg/errors, or else NewStacktrace()
+func GetOrNewStacktrace(err error, skip int, context int, appPackagePrefixes []string) *Stacktrace {
+	stacktracer, errHasStacktrace := err.(interface {
+		StackTrace() errors.StackTrace
+	})
+	if errHasStacktrace {
+		var frames []*StacktraceFrame
+		for _, f := range stacktracer.StackTrace() {
+			pc := uintptr(f) - 1
+			fn := runtime.FuncForPC(pc)
+			var file string
+			var line int
+			if fn != nil {
+				file, line = fn.FileLine(pc)
+			} else {
+				file = "unknown"
+			}
+			frame := NewStacktraceFrame(pc, file, line, context, appPackagePrefixes)
+			if frame != nil {
+				frames = append([]*StacktraceFrame{frame}, frames...)
+			}
+		}
+		return &Stacktrace{Frames: frames}
+	} else {
+		return NewStacktrace(skip + 1, context, appPackagePrefixes)
+	}
+}
+
+
 // Intialize and populate a new stacktrace, skipping skip frames.
 //
 // context is the number of surrounding lines that should be included for context.