patch 8.2.4774: crash when using a number for lambda name

Problem:    Crash when using a number for lambda name.
Solution:   Check the type of the lambda reference.
diff --git a/src/testdir/test_lambda.vim b/src/testdir/test_lambda.vim
index e6dcb67..8d06e59 100644
--- a/src/testdir/test_lambda.vim
+++ b/src/testdir/test_lambda.vim
@@ -66,6 +66,10 @@
   echo assert_fails('echo 10->{a -> a + 2}', 'E107:')
 
   call assert_fails('eval 0->(', "E110: Missing ')'")
+  call assert_fails('eval 0->(3)()', "E1275:")
+  call assert_fails('eval 0->([3])()', "E1275:")
+  call assert_fails('eval 0->({"a": 3})()', "E1275:")
+  call assert_fails('eval 0->(xxx)()', "E121:")
 endfunc
 
 func Test_not_lamda()