does not build with desktopintegration enabled

[teamcons]

../plugins/AppsPlugin/meson.build:10:4: ERROR: Tried to use 'add_project_arguments' after a build target has been declared. This is not permitted. Please declare all arguments before your targets.

I believe bc of:

desktopintegration = get_option('desktopintegration')

sources = [
    'Plugin.vala',
    'RelevancyService.vala'
]

if desktopintegration
    sources += 'DesktopIntegration.vala'
    add_project_arguments(['--define', 'DESKTOP_INTEGRATION'], language: 'vala')
endif