Merge pull request #47 from trocco-io/drop-stage-if-exists

Fix drop stage not exists

Author: yosuke-oka

src/main/java/org/embulk/output/snowflake/SnowflakeOutputConnection.java

@@ -85,7 +85,7 @@ protected String buildCreateStageSQL(StageIdentifier stageIdentifier) {
 
   protected String buildDropStageSQL(StageIdentifier stageIdentifier) {
     StringBuilder sb = new StringBuilder();
-    sb.append("DROP STAGE ");
+    sb.append("DROP STAGE IF EXISTS ");
     quoteStageIdentifier(sb, stageIdentifier);
     sb.append(";");
     return sb.toString();