change config handling (needs tests)

plugin/plugins/filesystem/filesystem.go

@@ -3,6 +3,7 @@ package filesystem
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -59,15 +60,17 @@ func (fs *FileSystemPlugin) Init(env *plugin.Environment) error {
 	}
 
 	cfg := &Config{}
-	if env.Config != nil {
-		byteRep, err := json.Marshal(env.Config)
-		if err != nil {
-			return err
-		}
-		if err = json.Unmarshal(byteRep, cfg); err != nil {
+	// config not being set is okay and will load defalts
+	// config being set with malformed data is not okay and will instruct the daemon to halt-and-catch-fire
+	rawConf, ok := (env.Config).(json.RawMessage)
+	if ok {
+		if err := json.Unmarshal(rawConf, cfg); err != nil {
 			return err
 		}
 	} else {
+		if env.Config != nil {
+			return fmt.Errorf("plugin config does not appear to be correctly formatted: %#v", env.Config)
+		}
 		cfg = defaultConfig(env.Repo)
 	}