Maximum iteration number exceeded

[PavelFil]

This code:

.grid {
    background: radial-gradient(circle, rgba(50, 0, 0, .5) 0, transparent 50%),
        radial-gradient(farthest-side circle, transparent 1%, green 5%, transparent 0),
        radial-gradient(farthest-side circle, transparent 11%, green 15%, transparent 0),
        radial-gradient(farthest-side circle, transparent 21%, green 25%, transparent 0),
        radial-gradient(farthest-side circle, transparent 31%, green 35%, transparent 0),
        radial-gradient(farthest-side circle, transparent 41%, green 45%, transparent 0),
        radial-gradient(farthest-side circle, transparent 51%, green 55%, transparent 0);
}

cause the error "Maximum iteration number exceeded (please fill an issue on https://github.com/csstree/csstree/issues)
syntax: [ , ]*".

This is a regular scenario for a value of the background property.