`scan_deps()` seems to fail when the input path is a file (not folder)

[TimTaylor]

scan_deps() seems to fail if the path input is a file rather than a folder.

This fails:

dir.create(f <- tempfile())
od <- setwd(f)
tryCatch(
    finally = {
        setwd(od)
        unlink(f, recursive = TRUE)
    }, 
    expr = {
        cat("dplyr::filter(mtcars, cyl == 4)\n", file = "example.R")
        pkgdepends::scan_deps("example.R", root = ".")    
    }
)
#> Error in `writeLines()`:
#> ! can only write character objects

This works:

dir.create(f <- tempfile())
od <- setwd(f)
tryCatch(
    finally = {
        setwd(od)
        unlink(f, recursive = TRUE)
    }, 
    expr = {
        dir.create("folder")
        cat("dplyr::filter(mtcars, cyl == 4)\n", file = "folder/example.R")
        pkgdepends::scan_deps("folder", root = ".")    
    }
)
#> 
#> Dependencies:
#> + dplyr @ example.R

^{Created on 2026-04-08 with reprex v2.1.1}