FIX: Refactor init_segmentation_wf initialization order

Author: mnoergaard

petprep/workflows/base.py

@@ -524,9 +524,6 @@ def init_single_subject_wf(subject_id: str):
                 ]),
             ])  # fmt:skip
 
-    if config.workflow.anat_only:
-        return clean_datasinks(workflow)
-
     segmentation_wf = init_segmentation_wf(
         seg=config.workflow.seg,
         name=f'pet_{config.workflow.seg}_seg_wf',
@@ -545,6 +542,9 @@ def init_single_subject_wf(subject_id: str):
         ]
     )
 
+    if config.workflow.anat_only:
+        return clean_datasinks(workflow)
+
     # Append the PET section to the existing anatomical excerpt
     # That way we do not need to filter down the number of PET datasets
     pet_pre_desc = f"""