TypeError: 'gdb.Value' object is not callable

I like writing code in Vala recently. I'm currently writing a little parser for Pidgin logs. However, when I try running it under gdb, I often get python tracebacks within my gdb backtrace that of the type TypeError: 'gdb.Value' object is not callable.

#4  0x08052d20 in pidgin_html_log_parser_parse (self=Traceback (most recent call last):
  File "/usr/share/glib-2.0/gdb/gobject.py", line 72, in to_string
    name = g_type_name_from_instance (self.val)
  File "/usr/share/glib-2.0/gdb/gobject.py", line 59, in g_type_name_from_instance
    name = g_type_to_name (gtype)
  File "/usr/share/glib-2.0/gdb/gobject.py", line 24, in g_type_to_name
    typenode = lookup_fundamental_type (typenode)
  File "/usr/share/glib-2.0/gdb/gobject.py", line 17, in lookup_fundamental_type
    return val[typenode >> 2].address()
TypeError: 'gdb.Value' object is not callable
, log_path=0x805deb8 "/home/user/file.html", protocol=
    0x8057448 [Protocol], my_account=0x80574c0 [Account], their_account=0x8057230 [Account], error=0xbfffef98)
    at /home/user/files/mine/development/projects/myproject/PidginLog.c:3009

After thinking about it for a little while, I realised that the issue must be that my class is somehow not a GObject. I was failing to extend from GLib.Object!

So, the affected classes have now changed from:

class Foo { ... }

to

class Foo : GLib.Object { ... }

and all is well with the world once more.

I'm surprised that there were few other questions about this online. Perhaps everyone else is more mindful than I or fewer people use Vala than I thought.