Build is producing gibberish for my cart, not sure why.
Hiya,

I have an otherwise-perfectly-fine .p8 file which is over the compressed size limit, so I'm trying to minify it. I tried this:

`./picotool/p8tool build dragondell.p8.png --lua dragondell.p8 --gfx dragondell.p8 --lua-minify`

and it produced no error, but when I run stats on the resulting .p8.png, I get:

```
dragondell.p8.png: Syntax error (remaining:b'\x15\x1a\x1c! \x1f\x01\x18\x1b\x0f \x18\x02\x17\x11%;\x18\x11\x12 9<:\x1e\x15\x13\x14<[!\x1c=C\x10\x1b#\x1a=M\x1b>D$\x023\x02\x039\x02\x049\x02\x059\x02\x069\x02\x079\x02\x08A\xaf\x0f\x1b\x18\x1b\x1e<\x16\x10\x11Bd=2;\x0e\x18 \x0f\x179<]\x10\x17\x0e\x18!\x11<\x8e\x1e\x11\x10=\x8b\x13\x1e\x11\x11C\x14?W\x1eD1@D\x1b\x18\x15"?v\x13\x1e %A`#\x14\x15 @\x7f@\x9d\x1b\x1e \x1a\x13Bx%\x11\x18\x18\x1b#@\x80B\xa7D\xbfA\xab\x1c\x15\x1aGw\x1c\x11 \x0f\x14L\xf0\x02\x089\x02\t9\x02\n9\x02\x0b9\x02\x0cM\x1bM/N\x10\x04N\x11\x04N\x12\x04N\x13\x04\x08SQ\x1e\x1b% \x18;N5\x1fP\x1a,G\xf4E\xf8\x11\x02-W?\x19 \x1c\x02 \x15\x18Qw<,;\x1e\x1bQ%<;\x0e!\x1f\x14<[ P\x12<\x9b \x1bX\x1d>?# \x18\x18<\x9b;=\x1aX\x1f\x04G\x1e\x05Y\x11\x07H\x10\x06Y\x16\x08Y*\tB\xa7#  \x11\x1e@t<\x1c;\x1fBa<_Q\x17=\x9e\x1a=\xce\x1a#_\x15\x07M\x1b\x06^\x1e\x06N\x1f\x08`\x12\x08\x04H\xa9\x0f\x1b\x15b\x18<{\x1f<l\x14\x11\x1fe\x1dJ<f\x1c>b]EL2\x1c\x18!P)\x08S\x1cS)\x05T\x1a\x07e\x1a\x07f!\x03N\xab_\x10\x1fAg\x10 \x15\x1f@m !\x18\x15N`\x19P\x14\x1e\x1b\x1b\x19j\x14\x06j\x15\x06M%Y\x18\x07L\xbd\x0f \x1f S\x1b\x1aKc=`Sc>PMs=`\x11A&^\x16\x06^\x17\x08o\x1a\x08\x07X\xaa\x1c\x1b\x1e ]\x1aV\x8c=Q\x0e\x1b  EAa\x1b\x08`g[=\x14\x11 \x1eMm\x11$\x0f\x18 \x19  \x15\x1bPg\x1f\x19\x1b\x17C#cOf\x13\x05\x01\x01\x01\x12!\x1a\x0f>$\x02!\x1a\x1cu\x10*{\x19\x12\x1e\x1b\x19`\x13\x1b+\x01\x02\x02\x02<>z\x12<7x\x18\x04=5 \x1b{\x15<\x15y\x19( >7\x15\x12>J1=, \x14\x11\x1a\x02\x1e\x11 !\x1e\x1a\x02\x11\x1a\x10@8<_ .A//9C\xd02\x7f\x1fC">.E\x84\x0f \x1e"\x11;E *$9\x02y\x1d\x19 &\x11EG\x86N\x10\x15oU\x87\xf7\x87\xf7\x87\x17o\x18I"\x8d\x17\x1f\x14!\x12\x12\x18\x11F)I\x15\x10\x11\x1eJK\x86\x18\x15\x88\x1e(A\'\x892\n') at line 1 char 1
dragondell.p8.png: could not load cart
```

I can load it into Pico-8, and the graphics look fine, but the code section is garbage.

Things I tried:
* Skipping `--lua-minify` has the same result (no error, graphics correct, code garbage).
* Skipping `--gfx` correctly minifies the code, but of course doesn't include the spritesheet.
  * Doing this and then using `build` again to add the graphics back in creates an unloadable cart like above.
  * Doing this then using `listlua` to output just the code and hand-copying that over the code in a copy of the working cart creates a cart which loads and runs, but has new bugs in it. :/

I see in the readme that picotool sometimes "rejects a cart with a syntax error but Pico-8 accepts it," which I suppose could be the case, but I'm not sure how I'd determine that, nor what the numbers in parentheses afterwards refer to (since they don't seem to be either issue numbers or cart numbers).

Any ideas what might be up, or anything else I can try? Apparently Github won't let me attach a .p8 file, but I'd be happy to send it to you another way if that's helpful. (It's a slightly newer and apparently slightly larger version of this one: https://www.lexaloffle.com/bbs/?tid=30999)

Thanks!