HPCC-17754 Correct test logic for boolean values

plugins/couchbase/couchbaseembed.cpp

@@ -772,7 +772,7 @@ namespace couchbaseembed
     {
         const char * value = nextField(field);
 
-        if (!value && !*value)
+        if (!value || !*value)
         {
             NullFieldProcessor p(field);
             return p.boolResult;