Added validation of mapgen weight

[PatrikLundell]

Summary

None

Purpose of change

Fix #75741, i.e. too high mapgen weights resulting in it being ignored.

Describe the solution

Add validation of weight parameters when parsing the JSON.

Describe alternatives you've considered

Tackle validation of other JSON parsing. Scope creep...

Testing

Result of loading world created according to the bug report description:
DEBUG : Error: Json error: data/mods/desert_region/mapgen/waterbody.json:20:14: <color_white><color_cyan>min value out of bounds (0 - 20,000,000)

],
"//": "Weight should be removed if/when lake_shore and river (or their weights) are unhardcoded",

<color_light_red> "weight": 100000000000,

<color_cyan>▲▲▲
"object": {
"fill_ter": "t_mudcrack",

FUNCTION : load_game
FILE : C:\Cataclysm-DDA\src\main_menu.cpp
LINE : 1103
VERSION : 0.G-11455-g8bbef0c5d2-dirty

When the offending entry had its weight adjusted no report was produced and the save loaded normally.

Verified that nothing blows up with the 20 million limit (there might have been existing extreme weights).

Additional context

• Note that I don't know WHY it fails. A large double number is converted to an int in the convoluted code mess, and that resulting number isn't > 0. However, preventing such numbers from being used should solve the problem.

• There are lots of other places were weights are use. Consider that to be out of scope.

• It's weird to parse double but then cast the values to int. Don't understand why a double is used at all.

• There are lots of places were int64 are parsed and then cast to ints. Again, that's out of scope.

• Decided on 20 million as the max limit to be reasonably sure you won't accidentally add yet another variant of something and then have things go weird. Note that I don't actually know how the weights are processed, but guess they're tallied up, in which case lots of large weights could push you over the limit. Anyway, 20 million should be more than enough for any real usage (trying to provide a huge number to drown out a base version is really a different issue: there's probably a need to have a way to reduce be base version's weight to 0 for mods). Again, out of scope.

• Encountered the error report in debug.log after the one produced by this PR, but only when the error is reported, not when the game is loaded normally:
  13:48:31.401 ERROR : C:\Cataclysm-DDA\src\flexbuffer_json.cpp:347 [error_skipped_members] (json-error)
  Json error: data/json/monsters/bird.json:193:17: <color_white><color_cyan>Invalid or misplaced field name "copy-from" in JSON data

  "id": "mon_chickadee_chick",

  "type": "MONSTER",

<color_light_red> "copy-from": "mon_generic_chick_tiny",

<color_cyan>▲▲▲
"upgrades": { "age_grow": 7, "into": "mon_chickadee" }
},

Providing it here in case it might be a genuine error that somehow is suppressed normally. The base assumption is that this is a result of the error report disrupting the parsing somehow, though.

[NetSysFire]

Tiny suggestion: specify what maxint (u32 vs u64) and/or simply list its value in the error. This would save the person a minute of figuring out what it means.

[PatrikLundell]

@NetSysFire:
Encountered this with the desertmod world:

Here pseudo terrain is generated in the middle of the land (the black tiles where the cursor is), which might be of interest to you, even though it's completely tangential to this PR itself.
Unfortunately, I didn't think to save the game, and I think it's the first time I've encountered it. Anyway, I doubt a save would really tell you much about what cause the issue.

[NetSysFire]

I saw those myself, too but thanks for confirming that these are not related to the horrible hacks I applied.