Fix that mistake.

Author: tsalo

niworkflows/interfaces/registration.py

@@ -462,13 +462,13 @@ def _run_interface(self, runtime):
 
         self._results["n_volumes_to_discard"] = n_volumes_to_discard
 
-        if multiecho and (len(self.inputs.in_file) < 2):
+        if self.inputs.multiecho and (len(self.inputs.in_file) < 2):
             raise ValueError("Argument 'multiecho' is True but "
                              "'in_file' has only one element")
 
         out_ref_fname = os.path.join(runtime.cwd, "ref_bold.nii.gz")
         if isdefined(self.inputs.sbref_file):
-            if multiecho and (len(self.inputs.sbref_file) < 2):
+            if self.inputs.multiecho and (len(self.inputs.sbref_file) < 2):
                 raise ValueError("Argument 'multiecho' is True but "
                                  "'sbref_file' has only one element")