MPS-19179 Build fails with null pointer: show more info
MPS-19179 Build fails with null pointer: check libraries exist before generation for better diagnostics
MPS-19179 Build fails with null pointer: do not throw NPE
Merge remote-tracking branch 'origin/MPS3.0'

Conflicts:
	core/tool/builder/source_gen/jetbrains/mps/tool/builder/make/GeneratorWorker.java