Save texture style without textures to remove texture style

Mentioned in 618ba51, it probably will be more natural this way - if there are no textures, we hide UV attribute to indicate that it won't be saved and on save we either do nothing, if texture style wasn't saved before, or remove it.

src/bonsai/bonsai/bim/module/style/operator.py

@@ -764,6 +764,7 @@ class EditSurfaceStyle(bpy.types.Operator, tool.Ifc.Operator):
         material.BIMStyleProperties.active_style_type = material.BIMStyleProperties.active_style_type
 
     def edit_existing_style(self):
+        ifc_file = tool.Ifc.get()
         material = tool.Ifc.get_object(self.style)
         assert self.surface_style
 
@@ -791,8 +792,9 @@ class EditSurfaceStyle(bpy.types.Operator, tool.Ifc.Operator):
             material = tool.Ifc.get_object(self.style)
             textures = self.get_texture_attributes()
             if not textures:
-                self.report({"ERROR"}, "Cannot save texture style without any textures.")
-                return {"CANCELLED"}
+                assert self.texture_style
+                ifcopenshell.api.style.remove_surface_style(ifc_file, self.texture_style)
+                return
             textures = tool.Ifc.run("style.add_surface_textures", textures=textures, uv_maps=[])
             texture_style = tool.Ifc.run(
                 "style.add_surface_style",
@@ -835,8 +837,7 @@ class EditSurfaceStyle(bpy.types.Operator, tool.Ifc.Operator):
             material = tool.Ifc.get_object(self.style)
             textures = self.get_texture_attributes()
             if not textures:
-                self.report({"ERROR"}, "Cannot create texture style without any textures.")
-                return {"CANCELLED"}
+                return
             textures = tool.Ifc.run("style.add_surface_textures", textures=textures, uv_maps=[])
             texture_style = tool.Ifc.run(
                 "style.add_surface_style",

src/bonsai/bonsai/bim/module/style/ui.py

@@ -220,7 +220,8 @@ class BIM_PT_styles(Panel):
         row = self.layout.row(align=True)
         row.label(text=f"Style has {len(textures)} textures", icon="SHADING_TEXTURE")
         row.operator("bim.add_surface_texture", text="", icon="ADD")
-        self.layout.prop(self.props, "uv_mode")
+        if textures:
+            self.layout.prop(self.props, "uv_mode")
 
         for i, texture in enumerate(textures):
             split = self.layout.split(factor=0.30, align=True)