FieldAccessDescriptorParser failures throw NPE

[damccorm]

An actual parser error is logged, but then a null pointer exception is thrown.

Example code:

FieldAccessDescriptor.withFieldNamesAs(ImmutableMap.of(""", """));

Logs:

line 1:0 token recognition error at: '"'
line 1:1 mismatched input '<EOF>' expecting {IDENTIFIER, '*'}

Imported from Jira BEAM-13696. Original Jira may contain additional context.
Reported by: ibzib.