Problem with updating terms in the multinom function

I am trying to add1 all interaction terms on top of a multinomial baseline model using multinom() but it shows the error

trying + x1:x2 
Error in if (trace) { : argument is not interpretable as logical
Called from: nnet.default(X, Y, w, mask = mask, size = 0, skip = TRUE, softmax = TRUE, 
    censored = censored, rang = 0, ...)

What is the problem here? I appreciate any input. Here is a reproducible example:

require(nnet)
data <- data.frame(y=sample(1:3, 24, replace = TRUE), 
        x1 = c(rep(1,12), rep(2,12)),
        x2 = rep(c(rep(1,4), rep(2,4), rep(3,4)),2),
        x3=rnorm(24),
        z1 = sample(1:10, 24, replace = TRUE))

m0 <- multinom(y ~ x1 + x2 + x3 + z1, data = data)
m1 <- add1(m0, scope = .~. + .^2, test="Chisq")

My end goal is to see which terms are appropriate to drop by later adding the line m1[order(add1.m1$'Pr(>Chi)'),].