Merge pull request #434 from bloxbean/fix_430

fix: Handle null or empty scriptHash in getScript method

Author: satran004

backend/src/main/java/com/bloxbean/cardano/client/backend/api/DefaultScriptSupplier.java

@@ -20,6 +20,9 @@ public DefaultScriptSupplier(ScriptService scriptService) {
 
     @Override
     public Optional<PlutusScript> getScript(String scriptHash) {
+        if (scriptHash == null || scriptHash.isEmpty())
+            return Optional.empty();
+
         try {
             var result = scriptService.getPlutusScript(scriptHash);
             if (result.isSuccessful())