patch 8.2.3229: Vim9: runtime and compile time type checks are not the same Commit: https://github.com/vim/vim/commit/4490ec4e839e45a2e6923c265c7e9e64c240b805 Author: Yegappan Lakshmanan <yegappan@yahoo.com> Date: Tue Jul 27 22:00:44 2021 +0200 patch 8.2.3229: Vim9: runtime and compile time type checks are not the same Problem: Vim9: runtime and compile time type checks are not the same. Solution: Add more runtime type checks for builtin functions. (Yegappan Lakshmanan, closes #8646)

--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -3808,11 +3808,16 @@ cmd_exists(char_u *name)
 f_fullcommand(typval_T *argvars, typval_T *rettv)
 {
     exarg_T  ea;
-    char_u   *name = argvars[0].vval.v_string;
+    char_u   *name;
     char_u   *p;
 
     rettv->v_type = VAR_STRING;
     rettv->vval.v_string = NULL;
+
+    if (in_vim9script() && check_for_string_arg(argvars, 0) == FAIL)
+	return;
+
+    name = argvars[0].vval.v_string;
     if (name == NULL)
 	return;