FIX: Interpolate derivative pipeline name in error message
@@ -171,7 +171,7 @@ def validate_derivative_paths(paths, layout=None, **kwargs):
raise BIDSDerivativesValidationError(
"Pipeline name '%s' has already been added "
"to this BIDSLayout. Every added pipeline "
- "must have a unique name!")
+ "must have a unique name!" % pipeline_name)
paths[pipeline_name] = deriv
return paths
