GIR writer: Fix critical warnings
GIR writer: Fix critical warnings

severinh/vala,frida/vala,rvu95/vala,frida/vala,phako/vala,tjol/vala-tjol,phako/vala,kamanashisroy/aroop,Jc2k/vala,severinh/vala,jessevdk/vala,tjol/vala-tjol,frida/vala,frida/vala,lovebug356/vala,spidermonkdust/vala,Jc2k/vala,jessevdk/vala,frida/vala,rvu95/vala,Distrotech/vala,kamanashisroy/aroop,kamanashisroy/aroop,GNOME/vala,jessevdk/vala,flobrosch/vala-fixes,severinh/vala,flobrosch/vala-fixes,rvu95/vala,spidermonkdust/vala,themiwi/vala,GNOME/vala,xdave/pvala,playya/vala,GNOME/vala,Distrotech/vala,lovebug356/vala,themiwi/vala,playya/vala,playya/vala,Distrotech/vala,spidermonkdust/vala,GNOME/vala,themiwi/vala,flobrosch/vala-fixes,tjol/vala-tjol