Substitution error for array element

Hocon:
```hocon
a {
  b: 0
  c: [
    "ccc"${a.b}
  ]
}
```

It will get exception:
`Hocon.HoconParserException : Substitution value must match the rest of the field type or empty. Array value type: String, substitution type: Number. At path 'a.b', line 5, position -2.`

Hocon below has no parsing exception:
```hocon
a {
  b: 0
  c: "ccc"${a.b}
}
```