floats not allowed in inc/dec statements

[thehowl]

package main

func main() {
        var i float64
        i++
}

$ gno run a.gno
panic running expression main(): unexpected type in in operation

main.runExpr.func1()
        /home/howl/oc/gno2/gnovm/cmd/gno/run.go:158 +0x138
panic({0xbeb9a0, 0xf46680})
        /usr/lib/go/src/runtime/panic.go:884 +0x213
github.com/gnolang/gno/gnovm/pkg/gnolang.(*Machine).doOpInc(0xc0000c4a20)
        /home/howl/oc/gno2/gnovm/pkg/gnolang/op_inc_dec.go:46 +0x55d

It seems to just be missing from the type switch.

(substituting inc/dec statements with x += 1 or x -= 1 works)