Backups in Stardog v7.0.2 are interrupted half way through (broken backups)

After migrating from Stardog 6 to Stardog 7 (7.0.2), we have problem with backups. Backups got interrupted with the following message:

INFO  2019-12-10 18:32:40,684 [stardog-user-14] com.complexible.stardog.index.Index:printInternal(314): Backing up: 64% complete in 00:02:47
ERROR 2019-12-10 18:32:42,463 [stardog-user-14] Error in creating backup
java.util.NoSuchElementException: No value present
        at java.util.Optional.get( ~[?:1.8.0_222]
        at com.complexible.stardog.index.memory.CompactValueSerializer.writeLiteral( ~[stardog-7.0.2.jar:?]
        at com.complexible.stardog.index.memory.ValueSerializer.write( ~[stardog-7.0.2.jar:?]

This results in an incomplete backup, which can not be restored. Backup functionality is not usable atm.

I believe this is the same issue which Eccenca has already reported. It's caused by invalid rdf:langString in the data. The fix will be in 7.1 scheduled for this week. The workaround is to fix the data, export it, and re-import into a new database.