inp.c: prevent crash upon if_inpdeck() returning NULL

src/frontend/inp.c

@@ -860,16 +860,18 @@ inp_dodeck(
         cktislinear(ckt, deck);
     /* set some output terminal data */
     out_init();
+    /* if_inpdeck() may return NULL upon error */
+    if (ckt) {
+        if (cp_getvar("warn", CP_NUM, &warn))
+            ckt->CKTsoaCheck = warn;
+        else
+            ckt->CKTsoaCheck = 0;
 
-    if (cp_getvar("warn", CP_NUM, &warn))
-        ckt->CKTsoaCheck = warn;
-    else
-        ckt->CKTsoaCheck = 0;
-
-    if (cp_getvar("maxwarns", CP_NUM, &maxwarns))
-        ckt->CKTsoaMaxWarns = maxwarns;
-    else
-        ckt->CKTsoaMaxWarns = 5;
+        if (cp_getvar("maxwarns", CP_NUM, &maxwarns))
+            ckt->CKTsoaMaxWarns = maxwarns;
+        else
+            ckt->CKTsoaMaxWarns = 5;
+    }
 
     ft_curckt->FTEstats->FTESTATdeckNumLines = 0;
     /*----------------------------------------------------