circumvent RangeError, which will be wrongly caught

Converting an integer via `T(number)` to some integer will cause a
range error, if it doesn't fit. Maybe it didn't in the past, which is
why the code worked before? Some other error was thrown?
With this code anyway it crashed, because it threw an internal error.

yaml/serialization.nim

@@ -199,7 +199,13 @@ proc constructObject*[T: int8|int16|int32|int64](
     elif item.scalarContent[0] == '0' and item.scalarContent.len > 1 and item.scalarContent[1] in {'o', 'O'}:
       result = parseOctal[T](s, item.scalarContent)
     else:
-      result = T(parseBiggestInt(item.scalarContent))
+      let nInt = parseBiggestInt(item.scalarContent)
+      if nInt <= T.high:
+        # make sure we don't produce a range error
+        result = T(nInt)
+      else:
+        # if outside of range, what to do?!
+        raise newException(YamlConstructionError, "AAA")
 
 proc constructObject*(s: var YamlStream, c: ConstructionContext,
                       result: var int)