Crash when constant is negative

[MoeShin]

package test_tygo

const A = -1

> tygo generate
unhandled unary expr: &{32 - 0xc00020aa40}
 *ast.UnaryExpr
panic: unhandled unary expr: &{32 - 0xc00020aa40}
 *ast.UnaryExpr

goroutine 1 [running]:
github.com/gzuidhof/tygo/tygo.(*PackageGenerator).writeType(0xc000208690, 0xc000087168, {0x69cd60?, 0xc00020aa60?}, 0x0, 0x8?)
        C:/Users/MoeShin/go/pkg/mod/github.com/gzuidhof/tygo@v0.2.10/tygo/write.go:114 +0x20a8
github.com/gzuidhof/tygo/tygo.(*PackageGenerator).writeValueSpec(0xc000208690, 0xc00020aa80, 0xc000258000, 0xc000087260)
        C:/Users/MoeShin/go/pkg/mod/github.com/gzuidhof/tygo@v0.2.10/tygo/write_toplevel.go:204 +0xb9b
github.com/gzuidhof/tygo/tygo.(*PackageGenerator).writeSpec(0xc000230100?, 0x3f?, {0x69cb80?, 0xc000258000?}, 0x510bfe?)
        C:/Users/MoeShin/go/pkg/mod/github.com/gzuidhof/tygo@v0.2.10/tygo/write_toplevel.go:65 +0xd5
github.com/gzuidhof/tygo/tygo.(*PackageGenerator).writeGroupDecl(0xc000208690, 0xc00020aa80?, 0xc000230100?)
        C:/Users/MoeShin/go/pkg/mod/github.com/gzuidhof/tygo@v0.2.10/tygo/write_toplevel.go:51 +0xfe
github.com/gzuidhof/tygo/tygo.(*PackageGenerator).Generate.func1({0x69b9a0?, 0xc0002220c0?})
        C:/Users/MoeShin/go/pkg/mod/github.com/gzuidhof/tygo@v0.2.10/tygo/package_generator.go:38 +0xcc
go/ast.inspector.Visit(0xc0002580a0, {0x69b9a0?, 0xc0002220c0?})
        C:/Users/MoeShin/scoop/apps/go/current/src/go/ast/walk.go:386 +0x2b
go/ast.Walk({0x69ad58?, 0xc0002580a0?}, {0x69b9a0?, 0xc0002220c0?})
        C:/Users/MoeShin/scoop/apps/go/current/src/go/ast/walk.go:51 +0x5c
go/ast.walkDeclList(...)
        C:/Users/MoeShin/scoop/apps/go/current/src/go/ast/walk.go:38
go/ast.Walk({0x69ad58?, 0xc0002580a0?}, {0x69b978?, 0xc00024a0a0?})
        C:/Users/MoeShin/scoop/apps/go/current/src/go/ast/walk.go:366 +0x1b05
go/ast.Inspect(...)
        C:/Users/MoeShin/scoop/apps/go/current/src/go/ast/walk.go:397
github.com/gzuidhof/tygo/tygo.(*PackageGenerator).Generate(0xc000208690)
        C:/Users/MoeShin/go/pkg/mod/github.com/gzuidhof/tygo@v0.2.10/tygo/package_generator.go:24 +0x532
github.com/gzuidhof/tygo/tygo.(*Tygo).Generate(0xc000087b58)
        C:/Users/MoeShin/go/pkg/mod/github.com/gzuidhof/tygo@v0.2.10/tygo/generator.go:65 +0x26e
github.com/gzuidhof/tygo/cmd.generate(0xc0000b0a00?, {0x619c5a?, 0x4?, 0x619c5e?})
        C:/Users/MoeShin/go/pkg/mod/github.com/gzuidhof/tygo@v0.2.10/cmd/root.go:45 +0x110
github.com/spf13/cobra.(*Command).execute(0xc000071680, {0x8de700, 0x0, 0x0})
        C:/Users/MoeShin/go/pkg/mod/github.com/spf13/cobra@v1.3.0/command.go:860 +0x67b
github.com/spf13/cobra.(*Command).ExecuteC(0xc000071400)
        C:/Users/MoeShin/go/pkg/mod/github.com/spf13/cobra@v1.3.0/command.go:974 +0x38d
github.com/spf13/cobra.(*Command).Execute(...)
        C:/Users/MoeShin/go/pkg/mod/github.com/spf13/cobra@v1.3.0/command.go:902
github.com/gzuidhof/tygo/cmd.Execute()
        C:/Users/MoeShin/go/pkg/mod/github.com/gzuidhof/tygo@v0.2.10/cmd/root.go:31 +0x2be
main.main()
        C:/Users/MoeShin/go/pkg/mod/github.com/gzuidhof/tygo@v0.2.10/main.go:6 +0xf