ref: Remove reliance on pkg/errors (#228)

We don't actually use anything out of this library except talking with
it's interfaces, so let's abstract out usage rather than forcing a
strong dependency on the library.

client.go

@@ -25,7 +25,6 @@ import (
 	"time"
 
 	"github.com/certifi/gocertifi"
-	pkgErrors "github.com/pkg/errors"
 )
 
 const (
@@ -743,7 +742,7 @@ func (client *Client) CaptureError(err error, tags map[string]string, interfaces
 	}
 
 	extra := extractExtra(err)
-	cause := pkgErrors.Cause(err)
+	cause := Cause(err)
 
 	packet := NewPacketWithExtra(err.Error(), extra, append(append(interfaces, client.context.interfaces()...), NewException(cause, GetOrNewStacktrace(cause, 1, 3, client.includePaths)))...)
 	eventID, _ := client.Capture(packet, tags)
@@ -768,7 +767,7 @@ func (client *Client) CaptureErrorAndWait(err error, tags map[string]string, int
 	}
 
 	extra := extractExtra(err)
-	cause := pkgErrors.Cause(err)
+	cause := Cause(err)
 
 	packet := NewPacketWithExtra(err.Error(), extra, append(append(interfaces, client.context.interfaces()...), NewException(cause, GetOrNewStacktrace(cause, 1, 3, client.includePaths)))...)
 	eventID, ch := client.Capture(packet, tags)
@@ -1054,3 +1053,29 @@ var hostname string
 func init() {
 	hostname, _ = os.Hostname()
 }
+
+// Cause returns the underlying cause of the error, if possible.
+// An error value has a cause if it implements the following
+// interface:
+//
+//     type causer interface {
+//            Cause() error
+//     }
+//
+// If the error does not implement Cause, the original error will
+// be returned. If the error is nil, nil will be returned without further
+// investigation.
+func Cause(err error) error {
+	type causer interface {
+		Cause() error
+	}
+
+	for err != nil {
+		cause, ok := err.(causer)
+		if !ok {
+			break
+		}
+		err = cause.Cause()
+	}
+	return err
+}

errors_test.go

@@ -4,8 +4,6 @@ import (
 	"fmt"
 	"reflect"
 	"testing"
-
-	pkgErrors "github.com/pkg/errors"
 )
 
 func TestWrapWithExtraGeneratesProperErrWithExtra(t *testing.T) {
@@ -47,7 +45,7 @@ func TestWrapWithExtraGeneratesProperErrWithExtra(t *testing.T) {
 func TestWrapWithExtraGeneratesCausableError(t *testing.T) {
 	baseErr := fmt.Errorf("this is bad")
 	testErr := WrapWithExtra(baseErr, nil)
-	cause := pkgErrors.Cause(testErr)
+	cause := Cause(testErr)
 
 	if !reflect.DeepEqual(cause, baseErr) {
 		t.Errorf("Failed to unwrap error, got %+v, expected %+v", cause, baseErr)

stacktrace.go

@@ -13,8 +13,6 @@ import (
 	"runtime"
 	"strings"
 	"sync"
-
-	"github.com/pkg/errors"
 )
 
 // Stacktrace defines Sentry's spec compliant interface holding Stacktrace information - https://docs.sentry.io/development/sdk-dev/interfaces/stacktrace/
@@ -56,32 +54,33 @@ type StacktraceFrame struct {
 
 // GetOrNewStacktrace tries 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 fName string
-			var file string
-			var line int
-			if fn != nil {
-				file, line = fn.FileLine(pc)
-				fName = fn.Name()
-			} else {
-				file = "unknown"
-				fName = "unknown"
-			}
-			frame := NewStacktraceFrame(pc, fName, file, line, context, appPackagePrefixes)
-			if frame != nil {
-				frames = append([]*StacktraceFrame{frame}, frames...)
-			}
+	type stackTracer interface {
+		StackTrace() []runtime.Frame
+	}
+	stacktrace, ok := err.(stackTracer)
+	if !ok {
+		return NewStacktrace(skip+1, context, appPackagePrefixes)
+	}
+	var frames []*StacktraceFrame
+	for f := range stacktrace.StackTrace() {
+		pc := uintptr(f) - 1
+		fn := runtime.FuncForPC(pc)
+		var fName string
+		var file string
+		var line int
+		if fn != nil {
+			file, line = fn.FileLine(pc)
+			fName = fn.Name()
+		} else {
+			file = "unknown"
+			fName = "unknown"
+		}
+		frame := NewStacktraceFrame(pc, fName, file, line, context, appPackagePrefixes)
+		if frame != nil {
+			frames = append([]*StacktraceFrame{frame}, frames...)
 		}
-		return &Stacktrace{Frames: frames}
 	}
-  return NewStacktrace(skip+1, context, appPackagePrefixes)
+	return &Stacktrace{Frames: frames}
 }
 
 // NewStacktrace intializes and populates a new stacktrace, skipping skip frames.