UNSUPPORTED_GENERATOR error class

The generator is not supported:

This error class has the following derived error classes:

MULTI_GENERATOR

only one generator allowed per <clause> clause but found <num>: <generators>

NESTED_IN_EXPRESSIONS

nested in expressions <expression>

NOT_GENERATOR

<functionName> is expected to be a generator. However, its class is <classCanonicalName>, which is not a generator.

OUTSIDE_SELECT

outside the SELECT clause, found: <plan>