[Bugfix] comment-changes: ExitCode in Case that Tag does not Exist

[kevinmatthes]

No description provided.

[github-actions]

Filename                            Stmts    Miss  Cover    Missing
--------------------------------  -------  ------  -------  ---------------------------------------
src/cff/cff_create.rs                 225       2  99.11%   237-245
src/cff/cffreference.rs               109       0  100.00%
src/increment_version.rs              179      26  85.47%   31-47, 122-124, 143, 149-154, 261-278
src/main.rs                             3       3  0.00%    22-24
src/complain.rs                       234      10  95.73%   30-71
src/version.rs                         69       0  100.00%
src/utilities.rs                       86       7  91.86%   22-26, 67-80, 148
src/running.rs                          8       0  100.00%
src/application.rs                     35      35  0.00%    32-146
src/macros.rs                          23       0  100.00%
src/changelog/ronlog.rs               223     158  29.15%   29-286, 352, 393-399
src/changelog/comment_changes.rs      275     275  0.00%    25-473
src/changelog/fragment.rs             128       2  98.44%   138, 146
src/graphing/graph.rs                 219       0  100.00%
src/graphing/agd.rs                   228       2  99.12%   356, 378
src/traits/append_as_line.rs           12       0  100.00%
src/traits/file_formats.rs             25       0  100.00%
src/traits/convert_buffer.rs           30       0  100.00%
src/traits/colour_message.rs           19       0  100.00%
src/traits/read_file.rs                56      34  39.29%   55-57, 72-74, 81-104, 109, 117-135, 142
src/traits/to_stderr.rs                 6       0  100.00%
src/traits/prefer.rs                    5       0  100.00%
src/pattern/buffer.rs                  33       0  100.00%
src/pattern/io_processor.rs            56      35  37.50%   90-152
src/pattern/writer.rs                 125      28  77.60%   134-139, 188-200, 232-245
TOTAL                                2411     617  74.41%