Try this.
query {
allTrustlines(
filter: {
assetcode: {equalTo: "HUG"},
issuer: {equalTo: "GD5T6IPRNCKFOHQWT264YPKOZAWUMMZOLZBJ6BNQMUGPWGRLBK3U7ZNP"},
}
) {
nodes {
issuer
accountid
assetcode
tlimit
}
}
}
The filter
key is probably what you’re after rather than the condition