Fix sometimes stream decode throw Invalid property name type object

[hans00]

Sometimes my server throw Invalid property name type.
I'm cannot provide the actual payload.
And I have no time to build mock payload to reproduce it.

P.S. my options:

{
  keyMap: {...},
  useRecords: false,
  pack: true,
}

[kriszyp]

I can't figure out how this would occur. What does the object look like that is being used as a key? It seems like we would at least want to add a src.length < position condition to this property assigment?