When an input file cannot be found, I get the following message:

Error { message: promise already under evaluation: recursive default argument reference or earlier problems? , call: read_data_frame(xcms_data_in, sprintf(\"%s input\", xcms_data_type)) }

I need a test to execute this path and to fix the issue, which may stem from setting the default value for an argument to a nested function to the value of a variable in the enclosing scope; e.g., this gives the promise error:

foo <- "hello"
bar <- function(foo = foo) { print(foo) }
bar()

but this does not:

foo <- "hello"
bar <- function(fee = foo) { print(fee) }
bar()