Make storiface.CallError json-friendly

extern/sector-storage/storiface/worker.go

@@ -2,6 +2,7 @@ package storiface
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"time"
@@ -104,22 +105,29 @@ const (
 )
 
 type CallError struct {
-	Code ErrorCode
+	Code    ErrorCode
-	Sub  error
+	Message string
+	sub     error
 }
 
 func (c *CallError) Error() string {
-	return fmt.Sprintf("storage call error %d: %s", c.Code, c.Sub.Error())
+	return fmt.Sprintf("storage call error %d: %s", c.Code, c.Message)
 }
 
 func (c *CallError) Unwrap() error {
-	return c.Sub
+	if c.sub != nil {
+		return c.sub
+	}
+
+	return errors.New(c.Message)
 }
 
 func Err(code ErrorCode, sub error) *CallError {
 	return &CallError{
-		Code: code,
+		Code:    code,
-		Sub:  sub,
+		Message: sub.Error(),
+
+		sub: sub,
 	}
 }
 

extern/sector-storage/worker_local.go

@@ -90,10 +90,7 @@ func newLocalWorker(executor ExecutorFunc, wcfg WorkerConfig, store stores.Store
 
 	go func() {
 		for _, call := range unfinished {
-			err := &storiface.CallError{
+			err := storiface.Err(storiface.ErrTempWorkerRestart, xerrors.New("worker restarted"))
-				Sub:  xerrors.New("worker restarted"),
-				Code: storiface.ErrTempWorkerRestart,
-			}
 
 			// TODO: Handle restarting PC1 once support is merged
 
@@ -261,10 +258,7 @@ func (l *LocalWorker) asyncCall(ctx context.Context, sector storage.SectorRef, r
 func toCallError(err error) *storiface.CallError {
 	var serr *storiface.CallError
 	if err != nil && !xerrors.As(err, &serr) {
-		serr = &storiface.CallError{
+		serr = storiface.Err(storiface.ErrUnknown, err)
-			Sub:  err,
-			Code: storiface.ErrUnknown,
-		}
 	}
 
 	return serr