NullPointerException in IonParser.nextToken()

[desaikd]

As per FasterXML/jackson-dataformats-binary#303, I was able to reproduce a NullPointerException when IonParser.nextToken() is called using the sample code. This eventually leads to LocalSymbolTable:681 according to the stack trace. The solution might be to just add a null check into the LocalSymbolTable code.

Stack trace for the exception:

com.amazon.ion.impl.LocalSymbolTable.readOneImport::LocalSymbolTable.java:681
com.amazon.ion.impl.LocalSymbolTable.prepImportsList::LocalSymbolTable.java:646
com.amazon.ion.impl.LocalSymbolTable.readLocalSymbolTable::LocalSymbolTable.java:304
com.amazon.ion.impl.LocalSymbolTable$Factory.newLocalSymtab::LocalSymbolTable.java:68
com.amazon.ion.impl.IonReaderBinaryUserX.has_next_helper_user::IonReaderBinaryUserX.java:252
com.amazon.ion.impl.IonReaderBinaryUserX.hasNext::IonReaderBinaryUserX.java:222
com.amazon.ion.impl.IonReaderBinaryUserX.next::IonReaderBinaryUserX.java:208
com.fasterxml.jackson.dataformat.ion.IonParser.nextToken::IonParser.java:506
com.fasterxml.jackson.databind.ObjectMapper._readTreeAndClose::ObjectMapper.java:4649
com.fasterxml.jackson.databind.ObjectMapper.readTree::ObjectMapper.java:3074
com.test.Entry.main::Entry.java:51

[popematt]

Fixed in #397