fix index error

src/base/utils/enzymes.jl

@@ -26,7 +26,7 @@ gene_product_mass_group_dict(model::GeckoModel, opt_model) =
     is_solved(opt_model) ?
     Dict(
         grp.group_id => dot(
-            value.(opt_model[:x])[(length(model.columns)+1).+grp.gene_product_idxs],
+            value.(opt_model[:x])[length(model.columns).+grp.gene_product_idxs],
             grp.gene_product_molar_masses,
         ) for grp in model.coupling_row_mass_group
     ) : nothing