NPE thrown when compiling schemas with noPva not set

This was reported by Frank Weiler on the user list. When compiling a set of schemas, an NPE is thrown if scomp is run with defaults. The compilation goes through if the -noPva option is used.

Attached below is the stack trace:
Exception in thread "main" java.lang.NullPointerException
at org.apache.xmlbeans.impl.schema.StscChecker.mapAndSum(StscChecker.java:624)
at org.apache.xmlbeans.impl.schema.StscChecker.isParticleValidRestriction(StscChecker.java:510)
at org.apache.xmlbeans.impl.schema.StscChecker.checkRestriction(StscChecker.java:379)
at org.apache.xmlbeans.impl.schema.StscChecker.checkAll(StscChecker.java:64)
at org.apache.xmlbeans.impl.schema.SchemaTypeSystemCompiler.compileImpl(SchemaTypeSystemCompiler.java:310)
at org.apache.xmlbeans.impl.schema.SchemaTypeSystemCompiler.compile(SchemaTypeSystemCompiler.java:181)
at org.apache.xmlbeans.impl.tool.SchemaCompiler.loadTypeSystem(SchemaCompiler.java:948)
at org.apache.xmlbeans.impl.tool.SchemaCompiler.compile(SchemaCompiler.java:1068)
at org.apache.xmlbeans.impl.tool.SchemaCompiler.main(SchemaCompiler.java:368)