patch 8.2.4051: compiler complains about possibly uninitialized variable

Problem:    Compiler complains about possibly uninitialized variable.
Solution:   Add code to avoid a compiler warning. (John Marriott)
diff --git a/src/scriptfile.c b/src/scriptfile.c
index c1ab415..7680fd5 100644
--- a/src/scriptfile.c
+++ b/src/scriptfile.c
@@ -274,7 +274,7 @@
 {
     static scid_T   last_current_SID = 0;
     int		    sid = ++last_current_SID;
-    scriptitem_T    *si;
+    scriptitem_T    *si = NULL;
 
     if (ga_grow(&script_items, (int)(sid - script_items.ga_len)) == FAIL)
     {
@@ -305,8 +305,10 @@
 # endif
     }
 
-    // Used to check script variable index is still valid.
-    si->sn_script_seq = current_sctx.sc_seq;
+    // "si" can't be NULL, check only to avoid a compiler warning
+    if (si != NULL)
+	// Used to check script variable index is still valid.
+	si->sn_script_seq = current_sctx.sc_seq;
 
     return sid;
 }