Add assert()s to show that jumps always land an an instruction that is between

1 and Vdbe.nOp-1.  Had these assert()s been in place before, they would have
caused an assertion fault for the byte-code error reported by
[forum:/forumpost/2482b32700|forum post 2482b32700].

FossilOrigin-Name: 8f8a58feb7047d19522ca32efbe42fd9ddf49aaf9064f7373eb56a88982406a2

src/vdbe.c

@@ -1043,6 +1043,8 @@ case OP_InitCoroutine: {     /* jump */
   /* Most jump operations do a goto to this spot in order to update
   ** the pOp pointer. */
 jump_to_p2:
+  assert( pOp->p2>0 );       /* There are never any jumps to instruction 0 */
+  assert( pOp->p2<p->nOp );  /* Jumps must be in range */
   pOp = &aOp[pOp->p2 - 1];
   break;
 }