in the day's of yore, i know a few folks who built tooling to validate and/or detect failure to sync between the IGP and LDP or detect data plane black holing behaviors caused by resolution in the RIB w/no complementary label allocation (or LDP convergence lagging significantly). implementations have come a long way since then. but yeah, IGP-LDP sync lag has been a thing for some folks.
No matter what the protocol, there will be occasional bugs, and we will continue to develop ad-hoc scripts to detect and workaround those when possible until such time that software upgrade is practical. None of these are practical to write ahead of time, as we won't know what the bug is we're trying to detect. This is not protocol discussion in itself, but we can make an argument that if there is bug probability per SLOC, less SLOC is less bugs, and label signalling in IGP is far simpler than LDP. -- ++ytti