Minor bug with fetch_arg_deparse

[kylebutts]

Super obscure bug, but figured I would report. If you pass a custom vcov function to vcov argument and namespace fixest::feols, then fetch_arg_deparse fails since mc[[1]] is fixest::feols which apparently has length > 1.

library(fixest)
feols(
  mpg ~ hp + i(cyl),
  data = mtcars, 
  vcov = function(x) { vcov(x, "hc1") }
)
#> OLS estimation, Dep. Var.: mpg
#> Observations: 32
#> Standard-errors: {vcov(x, "hc1")} 
#>              Estimate Std. Error  t value   Pr(>|t|)    
#> (Intercept) 28.650118   1.697237 16.88044 3.2885e-16 ***
#> hp          -0.024039   0.013201 -1.82096 7.9316e-02 .  
#> cyl::6      -5.967655   1.527542 -3.90670 5.3934e-04 ***
#> cyl::8      -8.520851   2.191241 -3.88860 5.6604e-04 ***
#> ---
#> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
#> RMSE: 2.94304   Adj. R2: 0.727485
fixest::feols(
  mpg ~ hp + i(cyl),
  data = mtcars, 
  vcov = function(x) { vcov(x, "hc1") }
)
#> Error in if (grepl("[tT]ry", mc[[1]])) next: the condition has length > 1