Fix some hscript crashes

[Reycko]

This PR fixes 2 crashes with HScript:

'Null Function Pointer' crash:

function onCountdownStarted()
{
  game.notes.thiswillcauseanerror(); // crash - null function pointer
}

'invalid field:' crash:

import flixel.FlxBasic;

function onCountdownStarted()
{
  var example = new FlxBasic();
  example.invalid = '123'; // crash - Invalid field:invalid
}

Fixes #16328

[LarryFrosty]

thank you blawg 🙏 i couldn't figure out how to do this
i do have a recommendation for the invalid field access error
the error is really barebones, it doesn't even have the customized posInfos
i recommend you take the code from the first catch and copy it over to the second catch

[Reycko]

Hi! I've commited a change that does what you requested

[LarryFrosty]

Hi! I've commited a change that does what you requested

Nice but maybe remove funcToRun from the error message so that the function doesn't show up twice

[Reycko]

This should be good. Thanks for taking your time with this.