Cawemo to Modeler fails for some milestsones

[charlieclark-onefiber]

Describe the bug

Conversion stops for an unknown reason

panic: interface conversion: interface {} is nil, not string

goroutine 1 [running]:
main.handleMilestone({0xc00019c344, 0x24}, 0xc0002344e0, 0x2)
	/Users/myuser/temp/camunda-7-to-8-migration/cawemo-to-web-modeler-migration/cawemo-to-web-modeler-migration.go:232 +0x325
main.handleMilestones({0xc000490660?, 0xc0001a4660?}, {0xc00019c344, 0x24}, 0x2)
	/Users/myuser/temp/camunda-7-to-8-migration/cawemo-to-web-modeler-migration/cawemo-to-web-modeler-migration.go:215 +0x115
main.handleFile(0xc0003290e0, {0x3?, 0xc0001c2940?}, {0xc0004742f4, 0x24})
	/Users/myuser/temp/camunda-7-to-8-migration/cawemo-to-web-modeler-migration/cawemo-to-web-modeler-migration.go:181 +0x627
main.handleFiles({0xc000022210, 0x24}, {0xc0004742f4, 0x24})
	/Users/myuser/temp/camunda-7-to-8-migration/cawemo-to-web-modeler-migration/cawemo-to-web-modeler-migration.go:127 +0x132
main.handleProject(0xc00008c1b0)
	/Users/myuser/temp/camunda-7-to-8-migration/cawemo-to-web-modeler-migration/cawemo-to-web-modeler-migration.go:118 +0x2fe
main.handleProjects()
	/Users/myuser/temp/camunda-7-to-8-migration/cawemo-to-web-modeler-migration/cawemo-to-web-modeler-migration.go:84 +0xa5
main.main()
	/Users/myuser/temp/camunda-7-to-8-migration/cawemo-to-web-modeler-migration/cawemo-to-web-modeler-migration.go:52 +0x196

Steps to reproduce

Compile Go project and run it.

Expected Behaviour

Conversion to run without errors

Library version

Unknown

Camunda Platform 7 version

Cawemo

Camunda Platform 8 version

Web modeler