./linearize-data.py linearize.cfg
Runs fine and reads all the blocks but seems to try to read the next blk file that does not exist.
I do get a bootstrap.dat file but I also get a "Premature end of block data". I can't tell if this is a normal ending to running the script or not.
That does not seem like the normal end of the script. That error means that it was unable to open the next file of block data which it was expecting. This could be due to a configuration error, or that perhaps the node is not synced to where you believe it to be. However, the resulting bootstrap.dat file should still be valid and usable. It just does not contain as many blocks as you expect it to contain.
How does one confirm that a bootsrtrap.dat is, in fact, accurate or properly done?
By trying to load it into a version of Bitcoin Core that can read the bootstrap.dat file and seeing if it does load it.