backends: remove log.Fatal and replace with error returns #5234

This changes the Config interface so that it returns an error.

backend/pcloud/pcloud.go

@@ -12,7 +12,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"log"
 	"net/http"
 	"net/url"
 	"path"
@@ -72,7 +71,7 @@ func init() {
 		Name:        "pcloud",
 		Description: "Pcloud",
 		NewFs:       NewFs,
-		Config: func(ctx context.Context, name string, m configmap.Mapper) {
+		Config: func(ctx context.Context, name string, m configmap.Mapper) error {
 			optc := new(Options)
 			err := configstruct.Set(m, optc)
 			if err != nil {
@@ -100,8 +99,9 @@ func init() {
 			}
 			err = oauthutil.Config(ctx, "pcloud", name, m, oauthConfig, &opt)
 			if err != nil {
-				log.Fatalf("Failed to configure token: %v", err)
+				return errors.Wrap(err, "failed to configure token")
 			}
+			return nil
 		},
 		Options: append(oauthutil.SharedOptions, []fs.Option{{
 			Name:     config.ConfigEncoding,