Encountering severe problems. Made a test game on Clavisson; some observations

1. game saving crashes (output see text below)
2. when trying to load a saved game, program crashes
3. all forester of the AI players (3) stay at home
4. there is (at least) one Port Spot which is not showing up as anchor (see attached picture)


== Output, probably at game saving ==

Writing Map Objects ...  Tribe immovable 'resi_gold2' has no owner!!  Tribe immovable 'resi_gold2' has no owner!!  Tribe immovable 'resi_gold2' has no owner!!  Tribe immovable 'resi_gold2' has no owner!!  Tribe immovable 'resi_gold2' has no owner!!  Tribe immovable 'resi_none' has no owner!!  Tribe immovable 'resi_coal2' has no owner!!  Tribe immovable 'resi_gold2' has no owner!! took 108ms
 Writing Flagdata Data ... took 5ms
 Writing Roaddata Data ... took 26ms
 Writing Buildingdata Data ... took 28ms
 Writing Node Ownership Data ... took 9ms
 Writing Exploration Data ... took 13ms
 Writing Players Unseen Data ... took 82ms
 Writing Scripting Data ... took 1466ms
 Writing Objective Data ... took 1ms
 Writing map images ... took 0ms
 MapSaver::save() for 'Calvisson' took 1899ms
Game: Writing Map Data took 1899ms
Game: Writing Player Economies Info ... took 2ms
Game: Writing ai persistent data ... took 0ms
Game: Writing Command Queue Data ... took 770ms
Game: Writing Interactive Player Data ... took 0ms
GameSaver::save() took 2965ms
SaveHandler::save_game() took 2965ms
Autosave: save took 2966 ms
TI(90371): destination appears to have become split from current location -> fail
TI(90289): destination appears to have become split from current location -> fail
TI(90501): destination disappeared or economy mismatch -> fail
TI(90131): destination appears to have become split from current location -> fail
TI(90473): destination appears to have become split from current location -> fail
TI(90545): destination appears to have become split from current location -> fail
TI(90313): destination appears to have become split from current location -> fail
TI(90518): destination appears to have become split from current location -> fail
TI(90553): destination appears to have become split from current location -> fail
TI(90500): destination appears to have become split from current location -> fail
 Internal error: Immovable at  64x166 does not match: is None but portspace_anchor was expected.
widelands: ../src/logic/map_objects/immovable.cc:130: void Widelands::BaseImmovable::unset_position(Widelands::EditorGameBase&, const Widelands::Coords&): Assertion `f.field->immovable == this' failed.
Aborted (core dumped)

== Output at game loading ==

Reading Exploration Data ... took 15ms
 Reading Flag Data ... took 102ms
 Reading Road Data ... took 4ms
 Reading Building Data ... took 57ms
 Reading Flagdata Data ... took 2ms
 Reading Roaddata Data ... took 88ms
 Reading Buildingdata Data ... took 18ms
 Second and third phase loading Map Objects ... WidelandsMapLoader::load_map_complete() for 'Calvisson' took 561ms
GameLoader::load() took 2509ms
Fatal exception: [../src/logic/map_objects/map_object.cc:676] Unknown MapObjectType 0.
FATAL ERROR - game crashed. Attempting emergency save.
terminate called after throwing an instance of 'WException'
  what():  [../src/logic/map_objects/map_object.cc:676] Unknown MapObjectType 0.
Aborted (core dumped)