feat: handle MaxVariables error limit exceeded

x/logic/interpreter/registry.go

@@ -2,12 +2,13 @@ package interpreter
 
 import (
 	"fmt"
-	orderedmap "github.com/wk8/go-ordered-map/v2"
 	"strconv"
 	"strings"
 
+	orderedmap "github.com/wk8/go-ordered-map/v2"
+
 	"github.com/ichiban/prolog"
-	engine "github.com/ichiban/prolog/engine"
+	"github.com/ichiban/prolog/engine"
 
 	"github.com/axone-protocol/axoned/v8/x/logic/predicate"
 )

x/logic/prolog/tuple.go

@@ -4,5 +4,5 @@ import "github.com/ichiban/prolog/engine"
 
 // Tuple is a predicate which unifies the given term with a tuple of the given arity.
 func Tuple(args ...engine.Term) engine.Term {
-	return engine.Atom(0).Apply(args...)
+	return engine.Atom("").Apply(args...)
 }

x/logic/util/prolog.go

@@ -54,16 +54,18 @@ func QueryInterpreter(
 			// error is not part of the look-ahead and should be included in the solutions
 			sdkCtx := sdk.UnwrapSDKContext(ctx)
 
+			var panicErr engine.PanicError
 			switch {
 			case errors.Is(callErr, types.LimitExceeded):
 				return nil, callErr
+			case errors.As(callErr, &panicErr) && errors.Is(panicErr.OriginErr, engine.ErrMaxVariables):
+				return nil, errorsmod.Wrapf(types.LimitExceeded, panicErr.OriginErr.Error())
 			case sdkCtx.GasMeter().IsOutOfGas():
 				return nil, errorsmod.Wrapf(
 					types.LimitExceeded, "out of gas: %s <%s> (%d/%d)",
 					types.ModuleName, callErr.Error(), sdkCtx.GasMeter().GasConsumed(), sdkCtx.GasMeter().Limit())
-			default:
-				results = append(results, types.Result{Error: callErr.Error()})
 			}
+			results = append(results, types.Result{Error: callErr.Error()})
 		} else {
 			// error is part of the look-ahead, so let's consider that there's one more solution
 			count = count.Incr()