patch 8.2.4653: "import autoload" does not check the file name

Problem:    "import autoload" does not check the file name.
Solution:   Give an error if the file is not readable. (closes #10049)
diff --git a/src/testdir/test_vim9_import.vim b/src/testdir/test_vim9_import.vim
index b1e96c5..c6a8206 100644
--- a/src/testdir/test_vim9_import.vim
+++ b/src/testdir/test_vim9_import.vim
@@ -2508,13 +2508,19 @@
       vim9script
       import autoload './doesNotExist.vim'
   END
-  v9.CheckScriptSuccess(lines)
+  v9.CheckScriptFailure(lines, 'E282:', 2)
 
   lines =<< trim END
       vim9script
       import autoload '/dir/doesNotExist.vim'
   END
-  v9.CheckScriptSuccess(lines)
+  v9.CheckScriptFailure(lines, 'E282:', 2)
+
+  lines =<< trim END
+      vim9script
+      import autoload '../testdir'
+  END
+  v9.CheckScriptFailure(lines, 'E17:', 2)
 
   lines =<< trim END
       vim9script