UI: Fix incorrect inactive status for curve properties

The "Geometry start & End" panel was grayed when using an object
to create the curve bevel. It should only be grayed out in this case
when no object is chosen in the "Bevel" subpanel.

release/scripts/startup/bl_ui/properties_data_curve.py

@@ -230,8 +230,8 @@ class DATA_PT_geometry_curve_start_end(CurveButtonsPanelCurve, Panel):
         col = layout.column()
 
         col.active = (
-            ((curve.bevel_depth > 0.0) or (curve.extrude > 0.0)) and
-            (curve.bevel_mode != 'OBJECT')
+            ((curve.bevel_depth > 0.0) or (curve.extrude > 0.0)) or
+            ((curve.bevel_mode == 'OBJECT') and curve.bevel_object is not None)
         )
         sub = col.column(align=True)
         sub.prop(curve, "bevel_factor_start", text="Factor Start")