Warn about incorrect use of `=` on squirrel table

[emma-miler]

In squirrel, using assignment operator = to set a key on a table will result in memory corruption if that key does not already exist. We should see if its viable to warn against this and let the user know to use <- operator instead.

[Erlite]

Not just memory corruption, the script silently stops its current execution. No errors, no warnings, just stops. And then you get a nice crash a while later if you're unlucky.

[GeckoEidechse]

We should see if its viable to warn against this and let the user know to use <- operator instead.

I think we should just raise full script error and let it crash with appropriate error message.

Do we have a mention of this in the wiki btw? As in people should check if table contains before writing to it?

[ASpoonPlaysGames]

I mean <- does everything = but better, = should never be used with tables really

[uniboi]

= should be used for reassigning a value in a table

[ASpoonPlaysGames]

<- also does it, if you want to avoid setting a new value in a table with <- just check if it exists beforehand, which you would have to do with = anyway to avoid this issue