global-state use inside expression?

[jatech1]

Hopefully a simple question... I am playing with the new global-state features in the style. I have it working when using it directly with a property:

"state": {
"stateVarName": {"default": "#00FF00FF"}
}

"line-color": ["global-state", "stateVarName"] // Works fine

But, can't figure out how to use it inside another expression:

"line-color": [
"match",
["get", "id"],
"T",
"rgba(0,0,0,1)",
["global-state", "stateVarName"] // Does not work; always returns null
]

Hopefully I am missing something simple? Any help would be appreciated!