The stack trace of python calls that resulted in this exception/failure was:
File: 'exec_python_func() autogenerated', lineno: 2, function: <module>
     0001:
 *** 0002:systemd_populate_packages(d)
     0003:
File: '/root/Work/Cust/user/src/iot-gw-base-os-yocto/yocto/sources/poky/meta/classes/systemd.bbclass', lineno: 161, function: systemd_populate_packages
     0157:    if os.path.exists(d.getVar("D")):
     0158:        for pkg in d.getVar('SYSTEMD_PACKAGES').split():
     0159:            systemd_check_package(pkg)
     0160:            if d.getVar('SYSTEMD_SERVICE_' + pkg):
 *** 0161:                systemd_generate_package_scripts(pkg)
     0162:        systemd_check_services()
     0163:}
     0164:
     0165:PACKAGESPLITFUNCS_prepend = "systemd_populate_packages "
File: '/root/Work/Cust/user/src/iot-gw-base-os-yocto/yocto/sources/poky/meta/classes/systemd.bbclass', lineno: 76, function: systemd_generate_package_scripts
     0072:
     0073:        postinst = d.getVar('pkg_postinst_%s' % pkg)
     0074:        if not postinst:
     0075:            postinst = '#!/bin/sh\n'
 *** 0076:        postinst += localdata.getVar('systemd_postinst')
     0077:        d.setVar('pkg_postinst_%s' % pkg, postinst)
     0078:
     0079:        prerm = d.getVar('pkg_prerm_%s' % pkg)
     0080:        if not prerm:
Exception: TypeError: Can't convert 'NoneType' object to str implicitly