Conversion of string vector to string scalar fails with "not a string object"

[clauswilke]

If a Rust function expecting a single string is handed a string vector from R, then it raises an error stating "not a string object". See here:

extendr/tests/extendrtests/tests/testthat/test-type-conversion.R

Line 29 in 9752c7f

expect_error(.Call(wrap__char_scalar, c("hello", "world")), "not a string object") # why this error message and not "Input must be of length 1"?

The error is appropriate, but the error message is confusing. A better error would be "Input must be of length 1", as is used for the other types, see e.g. here:

extendr/tests/extendrtests/tests/testthat/test-type-conversion.R

Line 7 in 9752c7f

expect_error(.Call(wrap__double_scalar, c(.45, .46)), "Input must be of length 1")