Show call in error

[hadley]

In testthat:

Error: unused argument (paths[[1]])
Backtrace:
 1. testthat::expect_equal(...) test-utils.R:20:2
 2. testthat:::expect_waldo_equal("equal", act, exp, info, ..., tolerance = tolerance)
 3. testthat:::waldo_compare(...)
 4. waldo::compare(x, y, ..., x_arg = x_arg, y_arg = y_arg)
 5. waldo:::compare_structure(x, y, paths = c(x_arg, y_arg), opts = opts) /Users/hadley/Documents/r-lib/waldo/R/compare.R:149:2
 6. waldo::compare_proxy(x, paths[[1]]) /Users/hadley/Documents/r-lib/waldo/R/compare.R:155:4

When called directly:

Error in compare_proxy.spec_tbl_df(x, paths[[1]]) : unused argument (paths[[1]])

[hadley]

Just needs a simple fix to exp_message().