Certain errors in accumulate functions cause compiler to throw NPE

The problem is caused by implementations of org.drools.compiler.compiler.Dialect.analyzeBlock returning null if an error is encountered. analyzeBlock (and similar methods) is called from a number of places, none of which seem to check the return value. Null checks could be added to all callers, but might it be better to throw an unchecked exception? This could be caught further up the stack in org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addRule where errors and warnings are retrieved from the context.

Does drools or drools-compiler have an exception handling policy? Is org.drools.compiler.lang.ParseException a suitable exception in this instance?

Example stack trace:

java.lang.NullPointerException
at org.drools.compiler.rule.builder.dialect.java.JavaAccumulateBuilder.buildAccumulator(JavaAccumulateBuilder.java:237)
at org.drools.compiler.rule.builder.dialect.java.JavaAccumulateBuilder.buildExternalFunctionCall(JavaAccumulateBuilder.java:172)
at org.drools.compiler.rule.builder.dialect.java.JavaAccumulateBuilder.build(JavaAccumulateBuilder.java:107)
at org.drools.compiler.rule.builder.dialect.java.JavaAccumulateBuilder.build(JavaAccumulateBuilder.java:72)
at org.drools.compiler.rule.builder.PatternBuilder.processSource(PatternBuilder.java:311)
at org.drools.compiler.rule.builder.PatternBuilder.build(PatternBuilder.java:181)
at org.drools.compiler.rule.builder.PatternBuilder.build(PatternBuilder.java:146)
at org.drools.compiler.rule.builder.PatternBuilder.build(PatternBuilder.java:127)
at org.drools.compiler.rule.builder.GroupElementBuilder.build(GroupElementBuilder.java:63)
at org.drools.compiler.rule.builder.RuleBuilder.build(RuleBuilder.java:99)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addRule(KnowledgeBuilderImpl.java:1759)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.compileRules(KnowledgeBuilderImpl.java:1047)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.compileAllRules(KnowledgeBuilderImpl.java:925)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addPackage(KnowledgeBuilderImpl.java:918)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addPackageFromDrl(KnowledgeBuilderImpl.java:459)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addKnowledgeResource(KnowledgeBuilderImpl.java:679)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:2204)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:2193)
at org.drools.compiler.CommonTestMethodBase.loadKnowledgeBaseFromString(CommonTestMethodBase.java:110)
at org.drools.compiler.integrationtests.AccumulateTest.getKieSessionFromContentStrings(AccumulateTest.java:3014)
at org.drools.compiler.integrationtests.AccumulateTest.testAccumulateWithCompilationError(AccumulateTest.java:1969)