Table with a generated column cycle results in a NullPointerException

[mrigger]

Consider the following statement:

CREATE TABLE t0(c0 BOOL AS (NOT c1), c1 BOOL AS (c0)); -- General error: "java.lang.NullPointerException"

Unexpectedly, the CREATE TABLE statement results in an error with the following stack trace:

Caused by: java.lang.NullPointerException
    at org.h2.expression.ExpressionColumn.getNotIfPossible(ExpressionColumn.java:409)
    at org.h2.expression.condition.ConditionNot.optimize(ConditionNot.java:50)
    at org.h2.table.Column.prepareExpressions(Column.java:473)
    at org.h2.command.ddl.CreateTable.update(CreateTable.java:127)
    at org.h2.command.CommandContainer.update(CommandContainer.java:173)
    at org.h2.command.Command.executeUpdate(Command.java:250)

I found this based on commit 30f0187.