Unexpected internal error has occurred.

[Rito13]

NML version

https://github.com/PeterN/nml/tree/station-bridges#

Error message

 nmlc ERROR: nmlc: An internal error has occurred:
nmlc-version: 0.4.5.post20250901+station.bridges.gb0a3bee1
Error:    (NotImplementedError) "reduce must be implemented in expression-subclass <class 'nml.actions.action2layout.StationSpriteset'>".
Command:  ['/usr/local/bin/nmlc', '-c', '--verbosity=4', '--no-optimisation-warning', '--grf=generated/Polish_Stations.grf', 'generated/Polish_Stations.nml']
Location: File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/expression/base_expression.py", line 70, in reduce

And with -s flag

  File "/usr/local/bin/nmlc", line 33, in <module>
    sys.exit(load_entry_point('nml==0.4.5.post20250901+station.bridges.gb0a3bee1', 'console_scripts', 'nmlc')())
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/main.py", line 637, in run
    main(sys.argv[1:])
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/main.py", line 343, in main
    ret = nml(
          ^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/main.py", line 447, in nml
    tmp_actions = result.get_action_list()
                  ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/ast/base_statement.py", line 164, in get_action_list
    action_list.extend(stmt.get_action_list())
                       ^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/ast/item.py", line 112, in get_action_list
    return base_statement.BaseStatementList.get_action_list(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/ast/base_statement.py", line 164, in get_action_list
    action_list.extend(stmt.get_action_list())
                       ^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/ast/item.py", line 271, in get_action_list
    return action3.parse_graphics_block(self, item_feature, item_id, item_size)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/actions/action3.py", line 289, in parse_graphics_block
    action_list.extend(parse_graphics_block_single_id(graphics_block, feature, id, is_livery_override))
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/actions/action3.py", line 355, in parse_graphics_block_single_id
    actions, var10map, registers_ref = action2layout.parse_station_layouts(
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/actions/action2layout.py", line 734, in parse_station_layouts
    layout_registers.parse(varact2parser)
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/actions/action2layout.py", line 527, in parse
    varact2parser.parse_expr(expr)
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/actions/action2var.py", line 692, in parse_expr
    self.parse(expr)
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/actions/action2var.py", line 701, in parse
    expr = self.preprocess_binop(expr)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/actions/action2var.py", line 411, in preprocess_binop
    return expr.reduce()
           ^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/expression/binop.py", line 80, in reduce
    expr1 = self.expr1.reduce(id_dicts)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/nml-0.4.5.post20250901+station.bridges.gb0a3bee1-py3.11-linux-x86_64.egg/nml/expression/base_expression.py", line 70, in reduce
    raise NotImplementedError("reduce must be implemented in expression-subclass {!r}".format(type(self)))
NotImplementedError: reduce must be implemented in expression-subclass <class 'nml.actions.action2layout.StationSpriteset'>

What caused it

spritelayout layout_FRONT_X {br}
	ground {br}
-		sprite: 1012;
+		sprite: CUSTOM(1) + 1;
	{_br}
	building {br}
		sprite: DEFAULT(1);
		zextent: {zextent};
		recolour_mode:	RECOLOUR_REMAP;
		palette:		CUSTOM(0);
	{_br}
{_br}

spritelayout layout_FRONT_Y {
	ground {
-		sprite: 1011;
+		sprite: CUSTOM(1);
	}
	building {
		sprite: DEFAULT(3);
		zextent: {zextent};
		recolour_mode:	RECOLOUR_REMAP;
		palette:		CUSTOM(0);
	}
}

+ switch (FEAT_STATIONS, SELF, GROUND_sprite_switch, terrain_type) {
+	TILETYPE_DESERT: 1037;
+	1011;
+ }

item (FEAT_STATIONS, tile_1_1) {
	graphics {
		sprite_layouts:	[layout_FRONT_X, layout_FRONT_Y];

// first spriteset always exist and has no cargo on it
		default:		spriteset_1_0;
-		custom_spritesets: [palette_switch];
+		custom_spritesets: [palette_switch, GROUND_sprite_switch];
		purchase:		spriteset_1_0;
		select_tile_type: 0; // can be 0 - 255 since nml 0.7.6
		PASS: random_1_PASS;
	}
}

NML file and files needed to compile

Polish_Stations.nml.zip
images.zip
lang.zip

Source code

https://codeberg.org/Rito12/OpenTTDPolishStations/src/branch/NML_internal_error_bug_report

[glx22]

GROUND_sprite_switch is not valid in custom_spritesets.
I think you need to use LOAD_TEMP in the layout and prepare_layout to fill the temp register.