fix: handle empty config values in getRepoConfig() (GH#680)

GetConfig() returns ("", nil) for missing/empty config keys.
getRepoConfig() then tried json.Unmarshal([]byte(""), ...) which
fails with "unexpected end of JSON input".

Add empty value check before JSON parsing - return empty map when
config value is empty string.

Closes GH#680

Co-Authored-By: dylan-conlin <dylan-conlin@users.noreply.github.com>

cmd/bd/repo.go

@@ -196,6 +196,11 @@ func getRepoConfig(ctx context.Context, store storage.Storage) (map[string]strin
 		return nil, err
 	}
 
+	// Handle empty value (config key exists but no value set)
+	if value == "" {
+		return make(map[string]string), nil
+	}
+
 	// Parse JSON map
 	repos := make(map[string]string)
 	if err := json.Unmarshal([]byte(value), &repos); err != nil {