V2SessionCatalog should not throw NoSuchDatabaseException in loadNamespaceMetadata

Author: Prashant Singh

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/V2SessionCatalog.scala

@@ -244,7 +244,7 @@ class V2SessionCatalog(catalog: SessionCatalog)
 
   override def loadNamespaceMetadata(namespace: Array[String]): util.Map[String, String] = {
     namespace match {
-      case Array(db) =>
+      case Array(db) if catalog.databaseExists(db) =>
         catalog.getDatabaseMetadata(db).toMetadata
 
       case _ =>

sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/v2/V2SessionCatalogSuite.scala

@@ -850,7 +850,7 @@ class V2SessionCatalogNamespaceSuite extends V2SessionCatalogBaseSuite {
   test("loadNamespaceMetadata: fail missing namespace") {
     val catalog = newCatalog()
 
-    val exc = intercept[NoSuchDatabaseException] {
+    val exc = intercept[NoSuchNamespaceException] {
       catalog.loadNamespaceMetadata(testNs)
     }