Add null-pointer checks to some code that crashed when trying

to .print results from a non-existent analysis.  Also remove the
troublesome .plot and .print lines from two examples.

examples/xspice/original-examples/diffpair.in

@@ -19,10 +19,10 @@ q4 7 7 9 qnl
 rbias 7 8 20k
 .model qnl npn(bf=80 rb=100 ccs=2pf tf=0.3ns tr=6ns cje=3pf cjc=2pf
 +   va=50)
-.print dc v(4) v(5)
-.plot dc v(5)
-.print ac vm(5) vp(5)
-.plot ac vm(5) vp(5)
+*.print dc v(4) v(5)
+*.plot dc v(5)
+*.print ac vm(5) vp(5)
+*.plot ac vm(5) vp(5)
 .print tran v(4) v(5)
 .plot tran v(5)
 .end

examples/xspice/original-examples/mosmem.in

@@ -21,7 +21,7 @@ m11 8 4 0 0 mod w=250u l=5u
 m12 9 9 8 0 mod w=5u   l=5u
 .model mod nmos(vto=0.5 phi=0.7 kp=1.0e-6 gamma=1.83 lambda=0.115
 +   level=1 cgso=1u cgdo=1u cbd=50p cbs=50p)
-.print dc v(5) v(6)
-.plot dc v(6)
+*.print dc v(5) v(6)
+*.plot dc v(6)
 .plot tran v(6) v(5) v(7) v(1) v(2)
 .end

src/spicelib/analysis/cktacct.c

@@ -57,11 +57,18 @@ CKTacct(CKTcircuit *ckt, JOB *anal, int which, IFvalue *val)
     case OPT_FILLNZ:
 	if ( ckt->CKTmatrix != NULL ) {
 #ifdef KLU
-	    if (ckt->CKTmatrix->CKTkluMODE)
-		val->iValue = ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNumeric->lnz + ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNumeric->unz
-                            - (int)ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNZ ;
-	    else
+	    if (ckt->CKTmatrix->CKTkluMODE) {
+                if (!ckt->CKTmatrix->SMPkluMatrix ||
+                    !ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNumeric) {
+                    return -1;
+                }
+		val->iValue =
+                    ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNumeric->lnz +
+                    ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNumeric->unz -
+                    (int)ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNZ ;
+	    } else {
 		val->iValue = spFillinCount(ckt->CKTmatrix->SPmatrix);
+            }
 #else
 	    val->iValue = spFillinCount(ckt->CKTmatrix->SPmatrix);
 #endif
@@ -72,10 +79,14 @@ CKTacct(CKTcircuit *ckt, JOB *anal, int which, IFvalue *val)
     case OPT_TOTALNZ:
 	if ( ckt->CKTmatrix != NULL ) {
 #ifdef KLU
-	    if (ckt->CKTmatrix->CKTkluMODE)
-		val->iValue = ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNumeric->lnz + ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNumeric->unz ;
-	    else
-		val->iValue = spElementCount(ckt->CKTmatrix->SPmatrix);
+	    if (ckt->CKTmatrix->CKTkluMODE && ckt->CKTmatrix->SMPkluMatrix &&
+                ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNumeric) {
+		val->iValue =
+                    ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNumeric->lnz +
+                    ckt->CKTmatrix->SMPkluMatrix->KLUmatrixNumeric->unz ;
+            } else {
+		val->iValue = 0;
+            }
 #else
 	    val->iValue = spElementCount(ckt->CKTmatrix->SPmatrix);
 #endif