fix bug with cat_out_only option

ObservationSim/ObservationSim.py

@@ -239,6 +239,7 @@ class Observation(object):
                 try:
                     if self.config["run_option"]["out_cat_only"]:
                         isUpdated = True
+                        pos_shear = 0.
                     elif chip.survey_type == "photometric" and not self.config["run_option"]["out_cat_only"]:
                         isUpdated, pos_shear = obj.drawObj_multiband(
                             tel=self.tel,
@@ -289,6 +290,8 @@ class Observation(object):
         # Detector Effects
         # ===========================================================
         # whether to output zero, dark, flat calibration images.
+
+        if not self.config["run_option"]["out_cat_only"]:
             chip.img = chip.addEffects(
                 config=self.config, 
                 img=chip.img,