patch 8.2.3997: Vim9: not enough testing for extend() and map()

Problem:    Vim9: not enough testing for extend() and map().
Solution:   Add more test cases.  Fix uncovered problems.  Remove unused type
            fields.
diff --git a/src/testdir/test_vim9_disassemble.vim b/src/testdir/test_vim9_disassemble.vim
index d4a5309..3a7642f 100644
--- a/src/testdir/test_vim9_disassemble.vim
+++ b/src/testdir/test_vim9_disassemble.vim
@@ -455,6 +455,7 @@
         '\d\+ CHECKTYPE string stack\[-1\] arg 2\_s*' ..
         '\d\+ STORE $1\_s*' ..
         '\d\+ SLICE 2\_s*' ..
+        '\d\+ SETTYPE list<any>\_s*' ..
         '\d\+ STORE $2\_s*' ..
         '\d\+ RETURN void',
         res)