Fixed checking of signal source type in connect method

object.go

@@ -225,6 +225,11 @@ param0 interface{}) {
 	if noi {
 		// There is no instance on which signal was emited as first parameter
 		poffset--
+	} else if !o.Type().Match(ft.In(poffset - 1)) {
+		panic(fmt.Sprintf(
+			"Callback #%d param. type %s doesn't match signal source: %s",
+			poffset-1, ft.In(poffset-1), o.Type(),
+		))
 	}
 	n_params := int(sq.n_params)
 	if ft.NumIn() != n_params+poffset {
@@ -242,7 +247,7 @@ param0 interface{}) {
 			if !pt[i].Match(ft.In(i + poffset)) {
 				panic(fmt.Sprintf(
 					"Callback #%d param. type %s doesn't match signal spec %s",
-					i+1, ft.In(i+poffset), pt[i],
+					i+poffset, ft.In(i+poffset), pt[i],
 				))
 			}
 		}