Attached chars may crash when using enemy redirection

[potsmugen]

Describe the bug

An attached character using enemy redirection can make Ikemen crash during match load.

Here's the crash log I got:

runtime error: index out of range
with length 0

goroutine 1 [running, locked to thread]:
github.com/yuin/gopher-lua.(*LState).PCall.func1()
   C:/Users/runneradmin/go/pkg/mod/github.com/yuin/[email protected]/state.go:1988 +0x212
panic({0x13f586b60, 0xc004333818})
   C:/hostedtoolcache/windows/go/1.20.6/x64/src/runtime/panic.go:884 +0x213
main.(*Char).enemy(0xc003c87500, 0x2)
   D:/a/Ikemen-GO/Ikemen-GO/src/char.go:2785 +0x338
main.BytecodeExp.run({0xc00a934600?, 0xc6, 0x100}, 0xc003c87500)
   D:/a/Ikemen-GO/Ikemen-GO/src/bytecode.go:1007 +0x741a
main.BytecodeExp.evalB({0xc00a934600?, 0xc00499e550?, 0xc00815f550?}, 0x1?)
   D:/a/Ikemen-GO/Ikemen-GO/src/bytecode.go:2135 +0x1e
main.StateBlock.Run({0x1, 0xffffffff, 0xfffffffe, 0x0, {0xc00a934600, 0xc6, 0x100}, 0x0, {0xc00833a600, 0x1, ...}, ...}, ...)
   D:/a/Ikemen-GO/Ikemen-GO/src/bytecode.go:2317 +0x37a
main.StateBlock.Run({0x1, 0xffffffff, 0xfffffffe, 0x0, {0x0, 0x0, 0x0}, 0x0, {0xc00390ec00, 0x3d, ...}, ...}, ...)
   D:/a/Ikemen-GO/Ikemen-GO/src/bytecode.go:2331 +0x4c6
main.(*StateBytecode).run(0xc003c87650, 0x0?)
   D:/a/Ikemen-GO/Ikemen-GO/src/bytecode.go:8524 +0x225
main.(*Char).changeStateEx(0xc003c87500, 0x8?, 0x8?, 0x1?, 0xffffffff, {0x0?, 0x0?})
   D:/a/Ikemen-GO/Ikemen-GO/src/char.go:3456 +0x297
main.(*Char).changeState(...)
   D:/a/Ikemen-GO/Ikemen-GO/src/char.go:3464
main.changeState.Run({0xc002ec45c0?, 0x0?, 0x0?}, 0x0?, {0x0?, 0x0?, 0x0?})
   D:/a/Ikemen-GO/Ikemen-GO/src/bytecode.go:2705 +0xf8
main.StateBlock.Run({0x1, 0xffffffff, 0xfffffffe, 0x0, {0x0, 0x0, 0x0}, 0x0, {0xc00bf34ea0, 0x1, ...}, ...}, ...)
   D:/a/Ikemen-GO/Ikemen-GO/src/bytecode.go:2331 +0x4c6
main.(*StateBytecode).run(0xc003c87650, 0xc003910ed0?)
   D:/a/Ikemen-GO/Ikemen-GO/src/bytecode.go:8524 +0x225
main.(*Char).actionRun(0xc003c87500)
   D:/a/Ikemen-GO/Ikemen-GO/src/char.go:5707 +0x6ff
main.(*CharList).action(0x13f50a920, 0x28c34335?, 0x433543541f02c21f?, 0x3543c73543c328c3?, 0x1f543543c328c343?, 0xc21fc243541f02c2?, 0x1f11cd02c511c315?, 0x4315111f1102c211?)
   D:/a/Ikemen-GO/Ikemen-GO/src/char.go:6376 +0x10b
main.(*System).action(0x13f509be0)
   D:/a/Ikemen-GO/Ikemen-GO/src/system.go:1328 +0x479
main.(*System).fight(0x13f509be0)
   D:/a/Ikemen-GO/Ikemen-GO/src/system.go:2058 +0x1426
main.systemScriptInit.func57.2()
   D:/a/Ikemen-GO/Ikemen-GO/src/script.go:979 +0x579
main.systemScriptInit.func57(0xc000106420)
   D:/a/Ikemen-GO/Ikemen-GO/src/script.go:1024 +0x3d3
github.com/yuin/gopher-lua.callGFunction(0xc000106420, 0x0)
   C:/Users/runneradmin/go/pkg/mod/github.com/yuin/[email protected]/vm.go:202 +0x37
github.com/yuin/gopher-lua.init.3.func26(0xc000106420, 0xc0c0001?, 0xc000205000?)
   C:/Users/runneradmin/go/pkg/mod/github.com/yuin/[email protected]/vm.go:821 +0x379
github.com/yuin/gopher-lua.mainLoop(0xc000106420, 0xc000175740?)
   C:/Users/runneradmin/go/pkg/mod/github.com/yuin/[email protected]/vm.go:31 +0xfa
github.com/yuin/gopher-lua.(*LState).callR(0xc000106420, 0x0, 0xffffffffffffffff, 0xc00000a7a8?)
   C:/Users/runneradmin/go/pkg/mod/github.com/yuin/[email protected]/state.go:1211 +0x1b4
github.com/yuin/gopher-lua.(*LState).Call(...)
   C:/Users/runneradmin/go/pkg/mod/github.com/yuin/[email protected]/state.go:1967
github.com/yuin/gopher-lua.(*LState).PCall(0xc000106420, 0x0, 0xc000175740?, 0x0)
   C:/Users/runneradmin/go/pkg/mod/github.com/yuin/[email protected]/state.go:2030 +0x145
github.com/yuin/gopher-lua.(*LState).DoFile(0xc000106420, {0xc0000158d8?, 0x0?})
   C:/Users/runneradmin/go/pkg/mod/github.com/yuin/[email protected]/auxlib.go:396 +0x6b
main.main()
   D:/a/Ikemen-GO/Ikemen-GO/src/main.go:90 +0x218

stack traceback:
   [G]: in function 'game'
   .\external\script\start.lua:1403: in function 'f_game'
   .\external\script\start.lua:1839: in function 'launchFight'
   external/script/default.lua:2: in function <external/script/default.lua:0>
   .\external\script\start.lua:1457: in function 'f'
   external/script/main.lua:3105: in function 'loop'
   external/script/main.lua:3189: in function 'loop'
   external/script/main.lua:4156: in main chunk
   [G]: ?

If all enemy redirections in the attached char are disabled, the crash no longer happens.

To Reproduce

Use this stage: terrymotw.zip

Start a 1 vs 3 match (curiously 3 vs 1 does not crash).

Expected behavior

No crash, of course.

Screenshots / Video

No response

Engine Version (or source code date)

25/07/2023 but also 0.98.2

Operating system

Windows

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