wat-desugar (1.0.33) seems to have an overflow issue for the `typeidx` of the `call_indirect` instruction.

e.g.:
This module (located [here](https://github.com/WebAssembly/spec/blob/master/test/core/ref_func.wast)):
``` wat
(module
  (func $f (import "M" "f") (param i32) (result i32))
  (func $g (param $x i32) (result i32)
    (i32.add (local.get $x) (i32.const 1))
  )

  (global funcref (ref.func $f))
  (global funcref (ref.func $g))
  (global $v (mut funcref) (ref.func $f))

  (global funcref (ref.func $gf1))
  (global funcref (ref.func $gf2))
  (func (drop (ref.func $ff1)) (drop (ref.func $ff2)))
  (elem declare func $gf1 $ff1)
  (elem declare funcref (ref.func $gf2) (ref.func $ff2))
  (func $gf1)
  (func $gf2)
  (func $ff1)
  (func $ff2)

  (func (export "is_null-f") (result i32)
    (ref.is_null (ref.func $f))
  )
  (func (export "is_null-g") (result i32)
    (ref.is_null (ref.func $g))
  )
  (func (export "is_null-v") (result i32)
    (ref.is_null (global.get $v))
  )

  (func (export "set-f") (global.set $v (ref.func $f)))
  (func (export "set-g") (global.set $v (ref.func $g)))

  (table $t 1 funcref)
  (elem declare func $f $g)

  (func (export "call-f") (param $x i32) (result i32)
    (table.set $t (i32.const 0) (ref.func $f))
    (call_indirect $t (param i32) (result i32) (local.get $x) (i32.const 0))
  )
  (func (export "call-g") (param $x i32) (result i32)
    (table.set $t (i32.const 0) (ref.func $g))
    (call_indirect $t (param i32) (result i32) (local.get $x) (i32.const 0))
  )
  (func (export "call-v") (param $x i32) (result i32)
    (table.set $t (i32.const 0) (global.get $v))
    (call_indirect $t (param i32) (result i32) (local.get $x) (i32.const 0))
  )
)
```
will look like this when run through `wat-desugar`:
``` wat
(module
  (import "M" "f" (func $f (param i32) (result i32)))
  (func $g (param $x i32) (result i32)
    local.get $x
    i32.const 1
    i32.add)
  (global (;0;) funcref (ref.func $f))
  (global (;1;) funcref (ref.func $g))
  (global $v (mut funcref) (ref.func $f))
  (global (;3;) funcref (ref.func $gf1))
  (global (;4;) funcref (ref.func $gf2))
  (func (;2;)
    ref.func $ff1
    drop
    ref.func $ff2
    drop)
  (elem (;0;) declare func $gf1 $ff1)
  (elem (;1;) declare func $gf2 $ff2)
  (func $gf1)
  (func $gf2)
  (func $ff1)
  (func $ff2)
  (func (;7;) (result i32)
    ref.func $f
    ref.is_null)
  (export "is_null-f" (func 7))
  (func (;8;) (result i32)
    ref.func $g
    ref.is_null)
  (export "is_null-g" (func 8))
  (func (;9;) (result i32)
    global.get $v
    ref.is_null)
  (export "is_null-v" (func 9))
  (func (;10;)
    ref.func $f
    global.set $v)
  (export "set-f" (func 10))
  (func (;11;)
    ref.func $g
    global.set $v)
  (export "set-g" (func 11))
  (table $t 1 funcref)
  (elem (;2;) declare func $f $g)
  (func (;12;) (param $x i32) (result i32)
    i32.const 0
    ref.func $f
    table.set $t
    local.get $x
    i32.const 0
    call_indirect $t (type 4294967295))
  (export "call-f" (func 12))
  (func (;13;) (param $x i32) (result i32)
    i32.const 0
    ref.func $g
    table.set $t
    local.get $x
    i32.const 0
    call_indirect $t (type 4294967295))
  (export "call-g" (func 13))
  (func (;14;) (param $x i32) (result i32)
    i32.const 0
    global.get $v
    table.set $t
    local.get $x
    i32.const 0
    call_indirect $t (type 4294967295))
  (export "call-v" (func 14))
  (type (;0;) (func (param i32) (result i32)))
  (type (;1;) (func))
  (type (;2;) (func (result i32))))
```

Notice that the `typeidx` of `call_indirect` is **4294967295** when it should be **0** (in this case).
desugar: overflow issue for typeidx of call_indirect instruction
This is a GitHub Issue
repo:wabt
owner:WebAssembly
Title : desugar: overflow issue for typeidx of call_indirect instruction
Issue date:

--- start body ---
wat-desugar (1.0.33) seems to have an overflow issue for the `typeidx` of the `call_indirect` instruction.

e.g.:
This module (located [here](https://github.com/WebAssembly/spec/blob/master/test/core/ref_func.wast)):
``` wat
(module
  (func $f (import "M" "f") (param i32) (result i32))
  (func $g (param $x i32) (result i32)
    (i32.add (local.get $x) (i32.const 1))
  )

  (global funcref (ref.func $f))
  (global funcref (ref.func $g))
  (global $v (mut funcref) (ref.func $f))

  (global funcref (ref.func $gf1))
  (global funcref (ref.func $gf2))
  (func (drop (ref.func $ff1)) (drop (ref.func $ff2)))
  (elem declare func $gf1 $ff1)
  (elem declare funcref (ref.func $gf2) (ref.func $ff2))
  (func $gf1)
  (func $gf2)
  (func $ff1)
  (func $ff2)

  (func (export "is_null-f") (result i32)
    (ref.is_null (ref.func $f))
  )
  (func (export "is_null-g") (result i32)
    (ref.is_null (ref.func $g))
  )
  (func (export "is_null-v") (result i32)
    (ref.is_null (global.get $v))
  )

  (func (export "set-f") (global.set $v (ref.func $f)))
  (func (export "set-g") (global.set $v (ref.func $g)))

  (table $t 1 funcref)
  (elem declare func $f $g)

  (func (export "call-f") (param $x i32) (result i32)
    (table.set $t (i32.const 0) (ref.func $f))
    (call_indirect $t (param i32) (result i32) (local.get $x) (i32.const 0))
  )
  (func (export "call-g") (param $x i32) (result i32)
    (table.set $t (i32.const 0) (ref.func $g))
    (call_indirect $t (param i32) (result i32) (local.get $x) (i32.const 0))
  )
  (func (export "call-v") (param $x i32) (result i32)
    (table.set $t (i32.const 0) (global.get $v))
    (call_indirect $t (param i32) (result i32) (local.get $x) (i32.const 0))
  )
)
```
will look like this when run through `wat-desugar`:
``` wat
(module
  (import "M" "f" (func $f (param i32) (result i32)))
  (func $g (param $x i32) (result i32)
    local.get $x
    i32.const 1
    i32.add)
  (global (;0;) funcref (ref.func $f))
  (global (;1;) funcref (ref.func $g))
  (global $v (mut funcref) (ref.func $f))
  (global (;3;) funcref (ref.func $gf1))
  (global (;4;) funcref (ref.func $gf2))
  (func (;2;)
    ref.func $ff1
    drop
    ref.func $ff2
    drop)
  (elem (;0;) declare func $gf1 $ff1)
  (elem (;1;) declare func $gf2 $ff2)
  (func $gf1)
  (func $gf2)
  (func $ff1)
  (func $ff2)
  (func (;7;) (result i32)
    ref.func $f
    ref.is_null)
  (export "is_null-f" (func 7))
  (func (;8;) (result i32)
    ref.func $g
    ref.is_null)
  (export "is_null-g" (func 8))
  (func (;9;) (result i32)
    global.get $v
    ref.is_null)
  (export "is_null-v" (func 9))
  (func (;10;)
    ref.func $f
    global.set $v)
  (export "set-f" (func 10))
  (func (;11;)
    ref.func $g
    global.set $v)
  (export "set-g" (func 11))
  (table $t 1 funcref)
  (elem (;2;) declare func $f $g)
  (func (;12;) (param $x i32) (result i32)
    i32.const 0
    ref.func $f
    table.set $t
    local.get $x
    i32.const 0
    call_indirect $t (type 4294967295))
  (export "call-f" (func 12))
  (func (;13;) (param $x i32) (result i32)
    i32.const 0
    ref.func $g
    table.set $t
    local.get $x
    i32.const 0
    call_indirect $t (type 4294967295))
  (export "call-g" (func 13))
  (func (;14;) (param $x i32) (result i32)
    i32.const 0
    global.get $v
    table.set $t
    local.get $x
    i32.const 0
    call_indirect $t (type 4294967295))
  (export "call-v" (func 14))
  (type (;0;) (func (param i32) (result i32)))
  (type (;1;) (func))
  (type (;2;) (func (result i32))))
```

Notice that the `typeidx` of `call_indirect` is **4294967295** when it should be **0** (in this case).
--- end body ---
