patch 8.2.1323: Vim9: invalid operators only rejected in :def function

Problem:    Vim9: invalid operators only rejected in :def function.
Solution:   Also reject them at script level. (closes #6564)
diff --git a/src/eval.c b/src/eval.c
index 81913c7..451bb16 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2420,9 +2420,9 @@
 {
     char_u	*p;
     int		getnext;
-    int		i;
     exptype_T	type = EXPR_UNKNOWN;
     int		len = 2;
+    int		type_is = FALSE;
 
     /*
      * Get the first variable.
@@ -2431,44 +2431,7 @@
 	return FAIL;
 
     p = eval_next_non_blank(*arg, evalarg, &getnext);
-    switch (p[0])
-    {
-	case '=':   if (p[1] == '=')
-			type = EXPR_EQUAL;
-		    else if (p[1] == '~')
-			type = EXPR_MATCH;
-		    break;
-	case '!':   if (p[1] == '=')
-			type = EXPR_NEQUAL;
-		    else if (p[1] == '~')
-			type = EXPR_NOMATCH;
-		    break;
-	case '>':   if (p[1] != '=')
-		    {
-			type = EXPR_GREATER;
-			len = 1;
-		    }
-		    else
-			type = EXPR_GEQUAL;
-		    break;
-	case '<':   if (p[1] != '=')
-		    {
-			type = EXPR_SMALLER;
-			len = 1;
-		    }
-		    else
-			type = EXPR_SEQUAL;
-		    break;
-	case 'i':   if (p[1] == 's')
-		    {
-			if (p[2] == 'n' && p[3] == 'o' && p[4] == 't')
-			    len = 5;
-			i = p[len];
-			if (!isalnum(i) && i != '_')
-			    type = len == 2 ? EXPR_IS : EXPR_ISNOT;
-		    }
-		    break;
-    }
+    type = get_compare_type(p, &len, &type_is);
 
     /*
      * If there is a comparative operator, use it.
@@ -2482,6 +2445,13 @@
 	if (getnext)
 	    *arg = eval_next_line(evalarg);
 
+	if (vim9script && type_is && (p[len] == '?' || p[len] == '#'))
+	{
+	    semsg(_(e_invexpr2), p);
+	    clear_tv(rettv);
+	    return FAIL;
+	}
+
 	// extra question mark appended: ignore case
 	if (p[len] == '?')
 	{