address comment

Author: ulysses-you

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala

@@ -1343,12 +1343,10 @@ class SessionCatalog(
 
   /**
    * Unregister a temporary or permanent function from a session-specific [[FunctionRegistry]]
+   * Return true if function exists.
    */
-  def unregisterFunction(name: FunctionIdentifier): Unit = {
-    if (!functionRegistry.dropFunction(name)) {
-      throw new NoSuchFunctionException(
-        formatDatabaseName(name.database.getOrElse(currentDb)), name.funcName)
-    }
+  def unregisterFunction(name: FunctionIdentifier): Boolean = {
+    functionRegistry.dropFunction(name)
   }
 
   /**

sql/core/src/main/scala/org/apache/spark/sql/execution/command/functions.scala

@@ -267,7 +267,9 @@ case class RefreshFunctionCommand(
       catalog.registerFunction(func, true)
     } else {
       // clear cached function, if not exists throw exception
-      catalog.unregisterFunction(identifier)
+      if (!catalog.unregisterFunction(identifier)) {
+        throw new NoSuchFunctionException(identifier.database.get, identifier.funcName)
+      }
     }
 
     Seq.empty[Row]