Doesn't work with {shinytest}

### Error description

```
> shinytest::recordTest()
Error in sd_startShiny(self, private, path, seed, loadTimeout, shinyOptions) :
Error starting application:
Loading required package: shiny
Warning: package 'shiny' was built under R version 4.0.5
Error in mapply(FUN = f, ..., SIMPLIFY = FALSE) :
Unable to load module "box/plot"; not found in "C:/Users/ismai/AppData/Local/Temp/RtmpgjcnP2"
(inside "find_in_path(spec, mod_search_path(caller))")
```

### R version

```plain text
platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
status
major 4
minor 0.2
year 2020
month 06
day 22
svn rev 78730
language R
version.string R version 4.0.2 (2020-06-22)
nickname Taking Off Again
```

### ‘box’ version

1.0.2

Start by reproducing shinytest::recordTest() on Windows with R 4.0.2 and box 1.0.2. Trace the sd_startShiny failure involving the missing box/plot module and verify that the application loads successfully through recordTest without the reported module-resolution error.

Written by the indexing model from the issue text.