fix: Panic when cause is nil while calling client.CaptureError (getse…

…ntry#261)

* Return deepest cause which is not nil

* Check if CaptureError works when cause is nil

client.go

@@ -1074,8 +1074,15 @@ func init() {
 //     }
 //
 // If the error does not implement Cause, the original error will
-// be returned. If the error is nil, nil will be returned without further
+// be returned.
+//
+// If the cause of the error is nil, then the original
+// error will be returned.
+//
+// If the error is nil, nil will be returned without further
 // investigation.
+//
+// Will return the deepest cause which is not nil.
 func Cause(err error) error {
 	type causer interface {
 		Cause() error
@@ -1086,7 +1093,13 @@ func Cause(err error) error {
 		if !ok {
 			break
 		}
-		err = cause.Cause()
+
+		if _cause := cause.Cause(); _cause != nil {
+			err = _cause
+		} else {
+			break
+		}
+
 	}
 	return err
 }

client_test.go

@@ -3,6 +3,7 @@ package raven
 import (
 	"encoding/json"
 	"fmt"
+	pkgErrors "github.com/pkg/errors"
 	"reflect"
 	"testing"
 	"time"
@@ -286,6 +287,41 @@ func TestCaptureNilError(t *testing.T) {
 	}
 }
 
+// Custom error which implements causer
+type customErr struct {
+	msg   string
+	cause error
+}
+
+func (e *customErr) Error() (errorMsg string) {
+	if e.msg != "" && e.cause != nil {
+		errorMsg = fmt.Sprintf("%v \n\t==>> %v", e.msg, e.cause)
+	} else if e.msg == "" && e.cause != nil {
+		errorMsg = fmt.Sprintf("%v", e.cause)
+	} else if e.msg != "" && e.cause == nil {
+		errorMsg = fmt.Sprintf("%s", e.msg)
+	}
+	return
+}
+
+// Implementing the causer interface from github.com/pkg/errors
+func (e *customErr) Cause() error {
+	return e.cause
+}
+
+func TestCaptureNilCauseError(t *testing.T) {
+	var client = DefaultClient
+	err := pkgErrors.WithStack(&customErr{
+		// Setting a nil cause
+		cause: nil,
+		msg:   "This is a test",
+	})
+	eventID := client.CaptureError(err, nil)
+	if eventID == "" {
+		t.Error("expected non-empty eventID:", eventID)
+	}
+}
+
 func TestNewPacketWithExtraSetsDefault(t *testing.T) {
 	testCases := []struct {
 		Extra    Extra