path: Check if JSONPath expression is NULL
path: Check if JSONPath expression is NULL

https://bugzilla.gnome.org/show_bug.cgi?id=708318

Distrotech/json-glib,GNOME/json-glib,Distrotech/json-glib,ebassi/json-glib,frida/json-glib,GNOME/json-glib,Distrotech/json-glib,ebassi/json-glib,ebassi/json-glib,frida/json-glib