Fixed NPE caused by Statement#getReturnType returning Null

CodeModel/src/main/java/org/openzen/zenscript/codemodel/statement/BlockStatement.java

 
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
 	public StoredType getReturnType() {
 		final List<StoredType> collect = Arrays.stream(statements)
 				.map(Statement::getReturnType)
+				.filter(Objects::nonNull)
 				.distinct()
 				.collect(Collectors.toList());
 		if(collect.isEmpty())

CodeModel/src/main/java/org/openzen/zenscript/codemodel/statement/ReturnStatement.java

 import org.openzen.zenscript.codemodel.expression.Expression;
 import org.openzen.zenscript.codemodel.expression.ExpressionTransformer;
 import org.openzen.zenscript.codemodel.scope.TypeScope;
+import org.openzen.zenscript.codemodel.type.BasicTypeID;
 import org.openzen.zenscript.codemodel.type.StoredType;
 
 /**
 	
 	@Override
 	public StoredType getReturnType() {
-		return value.type;
+		return value != null ? value.type : BasicTypeID.VOID.stored();
 	}
 	
 	@Override