WBS Plugin ist not showing any issues in project

[e13282a0]

Describe the bug
After installation the WBS plugin does not show the existing issues in the project

The request to https:///projects/70/wbs.json returns a status 500 internal server error

F, [2021-07-28T09:27:20.489288 #3556] FATAL -- :   
F, [2021-07-28T09:27:20.489613 #3556] FATAL -- : ActionView::Template::Error (TinyTds::Error: An expression of non-boolean type specified in a context where a condition is expected, near ')'.: EXEC sp_executesql N'SELECT COUNT(*) FROM [issues] INNER JOIN [projects] ON [projects].[id] = [issues].[project_id] WHERE (projects.status <> 9 AND EXISTS (SELECT 1 AS one FROM enabled_modules em WHERE em.project_id = projects.id AND em.name=''issue_tracking'')) AND [issues].[project_id] = @0 AND [issues].[id] NOT IN (SELECT [issues].[id] FROM [issues] INNER JOIN [projects] ON [projects].[id] = [issues].[project_id] INNER JOIN (SELECT [issues].* FROM [issues] INNER JOIN [projects] ON [projects].[id] = [issues].[project_id] WHERE (projects.status <> 9 AND EXISTS (SELECT 1 AS one FROM enabled_modules em WHERE em.project_id = projects.id AND em.name=''issue_tracking'')) AND [issues].[project_id] = 19 AND (issues.tracker_id IN (SELECT [trackers].[id] FROM [trackers] WHERE (trackers.id IN (N''8'',N''10'') OR trackers.fields_bits & 64)) OR issues.status_id IN (NULL))) parent WHERE (projects.status <> 9 AND EXISTS (SELECT 1 AS one FROM enabled_modules em WHERE em.project_id = projects.id AND em.name=''issue_tracking'')) AND [issues].[project_id] = @1 AND (issues.root_id = parent.root_id) AND (issues.lft >= parent.lft) AND (issues.rgt <= parent.rgt))', N'@0 int, @1 int', @0 = 19, @1 = 19):
F, [2021-07-28T09:27:20.490095 #3556] FATAL -- :     1: api.array :issues, api_meta(:total_count => @issues.count) do

    2:   wbs_grouped_issue_list(@issues) do |issue, level|

    3:     api.issue do

    4:       api.id issue.id

F, [2021-07-28T09:27:20.490368 #3556] FATAL -- :   
F, [2021-07-28T09:27:20.490624 #3556] FATAL -- : plugins/redmine_wbs/app/views/wbs/index.api.rsb:1:in `block in _plugins_redmine_wbs_app_views_wbs_index_api_rsb__42680501_213620'
lib/redmine/views/builders.rb:36:in `for'
plugins/redmine_wbs/app/views/wbs/index.api.rsb:1:in `_plugins_redmine_wbs_app_views_wbs_index_api_rsb__42680501_213620'
lib/redmine/sudo_mode.rb:61:in `sudo_mode'