From vscode extension version 25.3.0 whenever you have merge statement inside package body, this package ends up with compilation error:
Package Body TEST_PACKAGE compiled
Errors for PACKAGE BODY TEST_PACKAGE:
LINE/COL ERROR
-------- -----------------------------------------------------------------
24/16 PLS-00103: Encountered the symbol "end-of-file" when expecting one of the following:
;
The symbol ";" was substituted for "end-of-file" to continue.
This was not happening with extension version 25.2.2 and prior.
Example package definition:
CREATE OR REPLACE PACKAGE BODY test_package AS
  PROCEDURE merge_test AS
  BEGIN
    MERGE INTO employees e
    USING (
      SELECT 1,
             'A',
             'B'
        FROM dual
    ) ne ON ( e.employee_id = ne.employee_id )
    WHEN MATCHED THEN UPDATE
    SET e.first_name = ne.first_name,
        e.last_name = ne.last_name
    WHEN NOT MATCHED THEN
    INSERT (
      employee_id,
      first_name,
      last_name )
    VALUES
      ( ne.employee_id,
        ne.first_name,
        ne.last_name );
  END merge_test;
END test_package;
/
When you select all text (even with forward slash) and “Run statement” it will throw and error as written above.
Tested on sql developer extension for vscode version 25.3.0