Matcher doesn't perform EXIST correctly on key with value of embedded map

[nelio2k]

Given a data structure of:

	userData := map[string]interface{}{
		"KEY": map[string]interface{}{
			"internalKey": "value",
		},
	}

A filter expression of "KEY EXISTS" fails, even though technically it does exist.
From what I can tell, matchExec sees KEY, and then goes ahead and does 2 more token gets, which are ":" followed by "{".

Something like this:

NEIL DEBUG testMap: map[[$%XDCRInternalKey*%$]:TestDocKey Key:AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA [$%XDCRInternalMeta*%$]:map[AnotherXattr:TestValueString TestXattr:30]]
NEIL DEBUG Expr: $doc.[$%XDCRInternalMeta*%$] EXISTS
NEIL DEBUG objStart going into objOrArray
NEIL DEBUG tokenData: "[$%XDCRInternalKey*%$]"
NEIL DEBUG autostep tokenData: :
NEIL DEBUG autostep2 tokenData: "TestDocKey"
NEIL DEBUG KeyString: [$%XDCRInternalKey*%$]
NEIL DEBUG tokenData: "Key"
NEIL DEBUG autostep tokenData: :
NEIL DEBUG autostep2 tokenData: "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
NEIL DEBUG KeyString: Key
NEIL DEBUG tokenData: "[$%XDCRInternalMeta*%$]"
NEIL DEBUG autostep tokenData: :
NEIL DEBUG autostep2 tokenData: {
NEIL DEBUG KeyString: [$%XDCRInternalMeta*%$]
NEIL DEBUG KeyString found with token: 1 tokenData: { keyElem: :ops
[0] @ exists @

So it sees that there is no operations for tokenData "{" and then bails, and the original [0] got lost.