Fix IfcRailing modifier support spacing <= 0 would throw an error, and deactivate support spacing field if manual support is selected

src/blenderbim/blenderbim/bim/module/model/prop.py

@@ -563,7 +563,10 @@ class BIMRailingProperties(PropertyGroup):
         "If disabled, supports are added automatically based on the support spacing",
     )
     support_spacing: bpy.props.FloatProperty(
-        name="Support Spacing", default=1.0, description="Distance between supports if automatic supports are used"
+        name="Support Spacing", 
+        default=1.0, 
+        min=0.01,
+        description="Distance between supports if automatic supports are used",
     )
     railing_diameter: bpy.props.FloatProperty(name="Railing Diameter", default=0.050)
     clear_width: bpy.props.FloatProperty(

src/blenderbim/blenderbim/bim/module/model/ui.py

@@ -561,6 +561,11 @@ class BIM_PT_railing(bpy.types.Panel):
 
                 general_props = props.get_general_kwargs()
                 for prop in general_props:
+                    if prop == "support_spacing" and props.use_manual_supports:
+                        row = self.layout.row()
+                        row.prop(props, prop)
+                        row.active = False
+                        continue
                     self.layout.prop(props, prop)
 
                 update_railing_modifier_bmesh(context)