Length > 1 warning on from is.ggtrace_placeholder()

[yjunechoe]

Reprex

library(ggplot2)
ggplot(mtcars, aes(mpg, hp)) +
  geom_point(aes(color = as.factor(cyl)))

library(ggtrace)
l <- ggtrace_inspect_return(last_plot(), ggplot2:::guide_gengrob.legend, cond = 1)
#> Warning in .is_traced(what, where) || is.ggtrace_placeholder(._return):
#> 'length(x) = 4 > 1' in coercion to 'logical(1)'

l
#> TableGrob (7 x 6) "layout": 11 grobs
#>     z     cells       name                              grob
#> 1   1 (1-7,1-6) background rect[legend.background..rect.120]
#> 2   2 (2-2,2-5)      title             gTree[GRID.gTree.121]
#> 3   3 (4-4,2-2) key-3-1-bg        rect[legend.key..rect.111]
#> 4   4 (4-4,2-2)  key-3-1-1           points[GRID.points.112]
#> 5   5 (5-5,2-2) key-4-1-bg        rect[legend.key..rect.114]
#> 6   6 (5-5,2-2)  key-4-1-1           points[GRID.points.115]
#> 7   7 (6-6,2-2) key-5-1-bg        rect[legend.key..rect.117]
#> 8   8 (6-6,2-2)  key-5-1-1           points[GRID.points.118]
#> 9   9 (4-4,4-4)  label-3-3             gTree[GRID.gTree.122]
#> 10 10 (5-5,4-4)  label-4-3             gTree[GRID.gTree.123]
#> 11 11 (6-6,4-4)  label-5-3             gTree[GRID.gTree.124]
ggtrace::ggdraw_silent(l)

^{Created on 2022-12-06 with reprex v2.0.2}

Problem

Ugh I'm dumb:

ggtrace:::is.ggtrace_placeholder
#> function (x) 
#> class(x) == "ggtrace_placeholder"
#> <bytecode: 0x000001a9977850e0>
#> <environment: namespace:ggtrace>
ggtrace:::is.ggtrace_placeholder(l)
#> [1] FALSE FALSE FALSE FALSE

Should I use is()? That requires import from {methods} but it's stdlib so should be ok...

is(l, "ggtrace_placeholder")
#> [1] FALSE
is(ggtrace:::.ggtrace_placeholder, "ggtrace_placeholder")
#> [1] TRUE