fix(sdk/vm): improve MsgCall panic error message for wrong number of args

gno.land/pkg/sdk/vm/keeper.go

@@ -242,6 +242,11 @@ func (vm *VMKeeper) Call(ctx sdk.Context, msg MsgCall) (res string, err error) {
 	if cx.Varg {
 		panic("variadic calls not yet supported")
 	}
+	if len(msg.Args) < len(ft.Params) {
+		panic("not enough arguments in call to " + fnc)
+	} else if len(msg.Args) > len(ft.Params) {
+		panic("too many arguments in call to " + fnc)
+	}
 	for i, arg := range msg.Args {
 		argType := ft.Params[i].Type
 		atv := convertArgToGno(arg, argType)

gno.land/pkg/sdk/vm/keeper_test.go

@@ -395,3 +395,54 @@ func main() {
 	expectedString := fmt.Sprintf("hello world! %s\n", addr.String())
 	assert.Equal(t, res, expectedString)
 }
+
+func TestNumberOfArgsError(t *testing.T) {
+	env := setupTestEnv()
+	ctx := env.ctx
+
+	// Give "addr1" some gnots.
+	addr := crypto.AddressFromPreimage([]byte("addr1"))
+	acc := env.acck.NewAccountWithAddress(ctx, addr)
+	env.acck.SetAccount(ctx, acc)
+	env.bank.SetCoins(ctx, addr, std.MustParseCoins("10000000ugnot"))
+	assert.True(t, env.bank.GetCoins(ctx, addr).IsEqual(std.MustParseCoins("10000000ugnot")))
+
+	// Create test package.
+	files := []*std.MemFile{
+		{
+			Name: "test.gno",
+			Body: `package test
+
+import "std"
+
+func Echo(msg string) string {
+	return "echo:"+msg
+}`,
+		},
+	}
+	pkgPath := "gno.land/r/test"
+	msg1 := NewMsgAddPackage(addr, pkgPath, files)
+	err := env.vmk.AddPackage(ctx, msg1)
+	assert.NoError(t, err)
+
+	// Call Echo function with not enough arguments.
+	coins := std.MustParseCoins("1ugnot")
+	msg2 := NewMsgCall(addr, coins, pkgPath, "Echo", []string{})
+	assert.PanicsWithValue(
+		t,
+		func() {
+			env.vmk.Call(ctx, msg2)
+		},
+		"not enough arguments in call to Echo",
+	)
+
+	// Call Echo function with too many arguments.
+	msg3 := NewMsgCall(addr, coins, pkgPath, "Echo", []string{"hello world", "extra arg"})
+	assert.PanicsWithValue(
+		t,
+		func() {
+			env.vmk.Call(ctx, msg3)
+		},
+		"too many arguments in call to Echo",
+	)
+}