[app-builder] fix: avoid NullPointerException for unknown HTTP status codes (#595)

- Use getOrDefault() instead of get() in handleException method
- Return INTERNAL_SERVICE_ERROR when statusCode is not in exceptionMap
- Apply fix to both DataMateKnowledgeBaseManager and QianfanKnowledgeBaseManager

Author: loveTsong

app-builder/plugins/data-mate-knowledge/src/main/java/modelengine/fit/jade/datamate/knowledge/external/DataMateKnowledgeBaseManager.java

@@ -136,8 +136,9 @@ public DataMateRetrievalResult retrieve(String apiKey, DataMateRetrievalParam pa
 
     private KnowledgeException handleException(HttpClientResponseException ex) {
         int statusCode = ex.statusCode();
-        log.error(this.exceptionMap.get(statusCode).getMsg(), ex);
-        return new KnowledgeException(this.exceptionMap.get(statusCode), ex, ex.getSimpleMessage());
+        KnowledgeManagerRetCode retCode = this.exceptionMap.getOrDefault(statusCode, INTERNAL_SERVICE_ERROR);
+        log.error(retCode.getMsg(), ex);
+        return new KnowledgeException(retCode, ex, ex.getSimpleMessage());
     }
 
     private HttpClassicClient getHttpClient() {

app-builder/plugins/qianfan-knowledge/src/main/java/modelengine/jade/knowledge/external/QianfanKnowledgeBaseManager.java

@@ -119,8 +119,9 @@ public QianfanRetrievalResult retrieve(String apiKey, QianfanRetrievalParam para
 
     private KnowledgeException handleException(HttpClientResponseException ex) {
         int statusCode = ex.statusCode();
-        log.error(this.exceptionMap.get(statusCode).getMsg(), ex);
-        return new KnowledgeException(this.exceptionMap.get(statusCode), ex.getSimpleMessage());
+        KnowledgeManagerRetCode retCode = this.exceptionMap.getOrDefault(statusCode, INTERNAL_SERVICE_ERROR);
+        log.error(retCode.getMsg(), ex);
+        return new KnowledgeException(retCode, ex.getSimpleMessage());
     }
 
     private HttpClassicClient getHttpClient() {