a NPE is thrown when decision table has FIRST hit policy and result is null

Create decision table with FIRST hit policy and single column result Add decision row with "null" result Evaluate the decision table so the decision row with "null" result is matched NullPointerException is thrown ``` java.lang.NullPointerException: null     at java.base/java.util.Objects.requireNonNull(Objects.java:208)     at java.base/java.util.Optional.of(Optional.java:113)     at java.base/java.util.stream.FindOps$FindSink$OfRef.get(FindOps.java:194)     at java.base/java.util.stream.FindOps$FindSink$OfRef.get(FindOps.java:191)     at java.base/java.util.stream.FindOps$FindOp.evaluateSequential(FindOps.java:150)     at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)     at java.base/java.util.stream.ReferencePipeline.findFirst(ReferencePipeline.java:647)     at org.kie.dmn.feel.runtime.decisiontables.DecisionTableImpl.evaluateResults(DecisionTableImpl.java:303)     at org.kie.dmn.feel.runtime.decisiontables.DecisionTableImpl.evaluate(DecisionTableImpl.java:102)     at org.kie.dmn.feel.runtime.functions.DTInvokerFunction.invoke(DTInvokerFunction.java:50)     at org.kie.dmn.core.ast.DMNDTExpressionEvaluator.evaluate(DMNDTExpressionEvaluator.java:95)     at org.kie.dmn.core.ast.DMNContextEvaluator.evaluate(DMNContextEvaluator.java:97)     at org.kie.dmn.core.impl.DMNRuntimeImpl.evaluateDecision(DMNRuntimeImpl.java:672)     at org.kie.dmn.core.impl.DMNRuntimeImpl.evaluateAll(DMNRuntimeImpl.java:116) ```