patch 8.2.2635: Vim9: cannot define an inline function

Problem:    Vim9: cannot define an inline function.
Solution:   Make an inline function mostly work.
diff --git a/src/misc2.c b/src/misc2.c
index 70a19c1..90b8b58 100644
--- a/src/misc2.c
+++ b/src/misc2.c
@@ -2026,8 +2026,9 @@
 {
     int		i;
 
-    for (i = 0; i < gap->ga_len; ++i)
-	vim_free(((char_u **)(gap->ga_data))[i]);
+    if (gap->ga_data != NULL)
+	for (i = 0; i < gap->ga_len; ++i)
+	    vim_free(((char_u **)(gap->ga_data))[i]);
     ga_clear(gap);
 }