`convert' sometimes returns an error.

[shallit43]

Describe the bug
The `convert' command, which allows you to change the number system of an automaton provided the base-change is sensible (both powers of the same number), doesn't always work. Sometimes returns an error.

To Reproduce
Steps to reproduce the behavior:
Put the attached a163482base4.txt file in the Automata Library of Walnut. Then execute the command
convert $a163482 msd_2 $a163482base4;
and you get the following error (in Walnut v7.1.0):
java.lang.NullPointerException: Cannot invoke "it.unimi.dsi.fastutil.ints.IntList.getInt(int)" because the return value of "it.unimi.dsi.fastutil.ints.Int2ObjectRBTreeMap.get(int)" is null
at Automata.AutomatonLogicalOps.convertLsdBaseToRoot(AutomatonLogicalOps.java:632)

Expected behavior
Should create a new automaton a163482.txt accepting the same sequence, but in msd_2 format.

Desktop (please complete the following information):

• OS: Mac Sequoia 15.6
• Walnut Version v7.1.0

Additional context
Add any other context about the problem here.

a163482base4.txt

[jn1z]

Verified. This bug appears to be long-standing; from Walnut 5 (when convert was introduced):

[Walnut]$ convert $a163482 msd_2 $a163482base4;
java.lang.NullPointerException: Cannot invoke "java.util.List.get(int)" because the return value of "java.util.TreeMap.get(Object)" is null
at Automata.Automaton.convertLsdBaseToRoot(Automaton.java:1388)
at Automata.Automaton.convert(Automaton.java:1150)
at Main.Prover.convertCommand(Prover.java:1115)

[jn1z]

This may be a totalization issue (i.e. convert needs to totalize the input automaton, or as a workaround, the user inputs a totalized automaton).
Please see if the attached file matches what you expect.

a163482.txt

[jn1z]

Actually, I suspect that version is not correct because of the difference in totalized definition for DFAO vs DFA (sigh).