tests failing for edge functions

[robitalec]

Three warnings/errors for edge_dist and edge_nn:

longer object length is not a multiple of shorter object length

Different branches of j expression produced different auto-named columns: [NA!=distance]; using the most "last" names

When "returnDist" is TRUE, this error is added:
Internal error: jvnames is length 2 but ans is 4 and bynames is 1

[robitalec]

This was solved by assigning, within the j {}, the output list.

Eg. for edge_nn, from:

    if (returnDist) {
      w <- wm + (length(wm) * (as.numeric(names(wm)) - 1))
      list(ID = .SD[[1]][as.numeric(names(wm))],
           NN = .SD[[1]][wm],
           distance = distMatrix[w])
    } else {
      list(ID = .SD[[1]][as.numeric(names(wm))],
           NN = .SD[[1]][wm])
    }

to:

    if (returnDist) {
      w <- wm + (length(wm) * (as.numeric(names(wm)) - 1))
      l <- list(ID = .SD[[1]][as.numeric(names(wm))],
                NN = .SD[[1]][wm],
                distance = distMatrix[w])
    } else {
      l <- list(ID = .SD[[1]][as.numeric(names(wm))],
                NN = .SD[[1]][wm])
    }
    l

The if/else block here depends on a variable ("returnDist") passed to the function, that is set outside of the data.table chunk and doesn't change within it.

[robitalec]

Warnings+error present with data.table v.12.8 and not present with data.table v1.12.6.

Possibly related to Rdatatable/data.table#3802

[robitalec]

Closed by #25