Handle missing cardinalities graciously in case of uninitialized dimension storage.

Author: michael-mclawhorn

CHANGELOG.md

@@ -143,6 +143,8 @@ Current
 
 ### Fixed:
 
+- [Handle Number Format errors from empty or missing cardinality value](https://github.com/yahoo/fili/issues/549)
+
 - [Fix ConstantMaker make method with LogicalMetricInfo class](https://github.com/yahoo/fili/pull/540)
     * The ConstantMaker make method needs to be rewritten with the LogicalMetricInfo class.
 

fili-core/src/main/java/com/yahoo/bard/webservice/data/dimension/KeyValueStore.java

@@ -49,6 +49,18 @@ public interface KeyValueStore extends Closeable {
      */
     String get(@NotNull String key);
 
+    /**
+     * Get the value for a key from store or provide a default
+     *
+     * @param key  Key to get the value for
+     * @param defaultValue A default value in case key is null
+     *
+     * @return the value for corresponding key
+     */
+    default String getOrDefault(@NotNull String key, String defaultValue) {
+        return get(key) == null ? defaultValue : get(key);
+    }
+
     /**
      * Get the health status of the store.
      *

fili-core/src/main/java/com/yahoo/bard/webservice/data/dimension/impl/LuceneSearchProvider.java

@@ -205,7 +205,9 @@ public void setKeyValueStore(KeyValueStore keyValueStore) {
 
     @Override
     public int getDimensionCardinality() {
-        return Integer.parseInt(keyValueStore.get(DimensionStoreKeyUtils.getCardinalityKey()));
+        return Integer.parseInt(
+                keyValueStore.getOrDefault(DimensionStoreKeyUtils.getCardinalityKey(), "0")
+        );
     }
 
     @Override