Replace some unreachable branch instructions with assert() statements.

FossilOrigin-Name: 88b84bf18a4b27626f8a0a2d313706ddd4f13749
diff --git a/src/expr.c b/src/expr.c
index ec59f6d..2474635 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -3052,8 +3052,7 @@
   int i, n;
   assert( pList!=0 );
   assert( target>0 );
-  assert( pParse->pVdbe || pParse->db->mallocFailed );
-  if( pParse->pVdbe==0 ) return 0;
+  assert( pParse->pVdbe!=0 );  /* Never gets this far otherwise */
   n = pList->nExpr;
   for(pItem=pList->a, i=0; i<n; i++, pItem++){
     Expr *pExpr = pItem->pExpr;
diff --git a/src/vdbe.c b/src/vdbe.c
index c024c1c..90312ca 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -3484,7 +3484,7 @@
       pIdxKey = &r;
     }else{
       assert( pIn3->flags & MEM_Blob );
-      ExpandBlob(pIn3);
+      assert( (pIn3->flags & MEM_Zero)==0 );  /* zeroblobs already expanded */
       pIdxKey = sqlite3VdbeRecordUnpack(pC->pKeyInfo, pIn3->n, pIn3->z,
                                         aTempRec, sizeof(aTempRec));
       if( pIdxKey==0 ){