Fix join on some platforms

[gogonzo]

closes #230
Probably union on some platform doesn't take attributes into account (due to as.vector call). Also union/unique is not recommended for lists

?unique

[github-actions]

Code Coverage Summary

Filename                         Stmts    Miss  Cover    Missing
-----------------------------  -------  ------  -------  ---------
R/qenv-c.R                          57       0  100.00%
R/qenv-class.R                      12       0  100.00%
R/qenv-concat.R                      7       0  100.00%
R/qenv-constructor.R                 1       0  100.00%
R/qenv-errors.R                      4       4  0.00%    6-9
R/qenv-eval_code.R                  59       2  96.61%   111, 120
R/qenv-extract.R                    30       0  100.00%
R/qenv-get_code.R                   24       0  100.00%
R/qenv-get_env.R                     3       1  66.67%   27
R/qenv-get_messages.r                5       0  100.00%
R/qenv-get_var.R                    26       0  100.00%
R/qenv-get_warnings.R                5       0  100.00%
R/qenv-join.R                        7       7  0.00%    137-151
R/qenv-length.R                      2       1  50.00%   2
R/qenv-show.R                        1       1  0.00%    19
R/qenv-within.R                      8       0  100.00%
R/utils-get_code_dependency.R      189       1  99.47%   240
R/utils.R                           30       0  100.00%
TOTAL                              470      17  96.38%

Diff against main

Filename      Stmts    Miss  Cover
----------  -------  ------  --------
R/qenv-c.R       +2       0  +100.00%
TOTAL            +2       0  +0.02%

Results for commit: e93e097

Minimum allowed coverage is 80%

♻️ This comment has been updated with latest results

[github-actions]

Unit Tests Summary

  1 files   12 suites   3s ⏱️
148 tests 145 ✅ 3 💤 0 ❌
228 runs  225 ✅ 3 💤 0 ❌

Results for commit e93e097.

♻️ This comment has been updated with latest results.

[m7pr]

@gogonzo looks good, left a small comment

[gogonzo]

alternative PR merged