MOI interface fixes (#188)

* MOI fixes

* check variablestart too

Author: klamike

ext/ExaModelsMOI.jl

@@ -115,10 +115,16 @@ end
 
 function fill_variable_start!(moim, x0, param_vis)
     var_to_idx = Dict{MOI.VariableIndex,Int}()
-    for (i, vi) in enumerate(MOI.get(moim, MOI.ListOfVariableIndices()))
+    i = 0
+    for vi in MOI.get(moim, MOI.ListOfVariableIndices())
         vi ∈ param_vis && continue
+        i += 1
         var_to_idx[vi] = i
-        start = MOI.get(moim, MOI.VariablePrimalStart(), vi)
+        start = if MOI.supports(moim, MOI.VariablePrimalStart(), typeof(vi))
+            MOI.get(moim, MOI.VariablePrimalStart(), vi)
+        else
+            nothing
+        end
         isnothing(start) && continue
         x0[i] = start
     end
@@ -307,8 +313,14 @@ function exafy_con(
     for (i, ci) in enumerate(cons)
         func = MOI.get(moim, MOI.ConstraintFunction(), ci)
         set = MOI.get(moim, MOI.ConstraintSet(), ci)
-        start = MOI.get(moim, MOI.ConstraintPrimalStart(), ci)
         con_to_idx[ci] = offset + i
+        start = if MOI.supports(
+            moim, MOI.ConstraintPrimalStart(), typeof(ci)
+        )
+            MOI.get(moim, MOI.ConstraintPrimalStart(), ci)
+        else
+            nothing
+        end
         _exafy_con_update_start(ci, start, y0, con_to_idx)
         _exafy_con_update_vector(ci, set, lcon, ucon, con_to_idx)
         bin = _exafy_con(ci, func, bin, var_to_idx, con_to_idx)