create scratch SV early, destroy wrap after push SV

typemap

@@ -89,21 +89,21 @@ T_OPENCV_VECTOR
   PDL_CORE_(barf_if_error)(*(pdl_error *)&CW_err);
   AV *av = newAV(); av_extend(av, sz);
   for (i = 0; i < sz; i++) {
+    SV* pxsv = newSV(0);
+    if (!pxsv) PDL_CORE_(pdl_barf)(\"Failed to create SV\");
     PDL_Indx d1, d2, d3; pdl_datatypes dt;
     cw_Mat_pdlDims(wrap2[i], &dt, &d1, &d2, &d3);
     pdl* px = PDL_CORE_(pdlnew)();
     if (!px) PDL_CORE_(pdl_barf)(\"Failed to create pdl\");
-    SV* pxsv = newSV(0);
-    if (!pxsv) PDL_CORE_(pdl_barf)(\"Failed to create SV\");
     PDL_CORE_(SetSV_PDL)(pxsv, px);
     PDL_Indx pdims[] = { d1, d2, d3 };
     PDL_CORE_(barf_if_error)(PDL->setdims(px,pdims,3));
     px->datatype = dt;
     PDL_CORE_(barf_if_error)(PDL_CORE_(make_physical)(px));
     CW_err = cw_${(my $novecstar=$type)=~s/^vector_(.*)Wrapper\s*\**$/$1/; \$novecstar}_copyDataTo(wrap2[i], px->data, px->nbytes);
-    cw_${(my $novecstar=$type)=~s/^vector_(.*)Wrapper\s*\**$/$1/; \$novecstar}_DESTROY(wrap2[i]);
     PDL_CORE_(barf_if_error)(*(pdl_error *)&CW_err);
     if (!av_store(av, i, pxsv)) PDL_CORE_(pdl_barf)(\"Failed to push SV\");
+    cw_${(my $novecstar=$type)=~s/^vector_(.*)Wrapper\s*\**$/$1/; \$novecstar}_DESTROY(wrap2[i]);
   }
   cw_${(my $nostar=$type)=~s/Wrapper\s*\**$//; \$nostar}_DESTROY($var);
   sv_setsv($arg, newRV_noinc((SV*)av));