mypy: Add check for parse_user_agent returning None in compatibility.py.
mypy: Add check for parse_user_agent returning None in compatibility.py.

punchagan/zulip,punchagan/zulip,vabs22/zulip,rishig/zulip,kou/zulip,dhcrzf/zulip,jackrzhang/zulip,verma-varsha/zulip,rishig/zulip,jrowan/zulip,punchagan/zulip,shubhamdhama/zulip,shubhamdhama/zulip,kou/zulip,showell/zulip,hackerkid/zulip,vabs22/zulip,hackerkid/zulip,vaidap/zulip,tommyip/zulip,andersk/zulip,andersk/zulip,dhcrzf/zulip,mahim97/zulip,verma-varsha/zulip,mahim97/zulip,tommyip/zulip,synicalsyntax/zulip,andersk/zulip,zulip/zulip,brainwane/zulip,tommyip/zulip,Galexrt/zulip,showell/zulip,synicalsyntax/zulip,rht/zulip,tommyip/zulip,mahim97/zulip,showell/zulip,eeshangarg/zulip,zulip/zulip,kou/zulip,zulip/zulip,verma-varsha/zulip,punchagan/zulip,eeshangarg/zulip,amanharitsh123/zulip,amanharitsh123/zulip,verma-varsha/zulip,zulip/zulip,rht/zulip,jackrzhang/zulip,shubhamdhama/zulip,Galexrt/zulip,timabbott/zulip,dhcrzf/zulip,andersk/zulip,vabs22/zulip,rht/zulip,brockwhittaker/zulip,amanharitsh123/zulip,verma-varsha/zulip,synicalsyntax/zulip,synicalsyntax/zulip,rishig/zulip,andersk/zulip,rht/zulip,jackrzhang/zulip,rishig/zulip,dhcrzf/zulip,eeshangarg/zulip,vaidap/zulip,rishig/zulip,brockwhittaker/zulip,brainwane/zulip,rishig/zulip,zulip/zulip,dhcrzf/zulip,dhcrzf/zulip,eeshangarg/zulip,jackrzhang/zulip,eeshangarg/zulip,jackrzhang/zulip,shubhamdhama/zulip,tommyip/zulip,vabs22/zulip,eeshangarg/zulip,showell/zulip,hackerkid/zulip,synicalsyntax/zulip,timabbott/zulip,showell/zulip,vabs22/zulip,shubhamdhama/zulip,punchagan/zulip,rht/zulip,brockwhittaker/zulip,amanharitsh123/zulip,synicalsyntax/zulip,rht/zulip,vaidap/zulip,punchagan/zulip,zulip/zulip,brockwhittaker/zulip,tommyip/zulip,mahim97/zulip,verma-varsha/zulip,Galexrt/zulip,Galexrt/zulip,kou/zulip,hackerkid/zulip,timabbott/zulip,brainwane/zulip,amanharitsh123/zulip,mahim97/zulip,shubhamdhama/zulip,kou/zulip,hackerkid/zulip,tommyip/zulip,Galexrt/zulip,zulip/zulip,shubhamdhama/zulip,kou/zulip,brainwane/zulip,timabbott/zulip,amanharitsh123/zulip,timabbott/zulip,jrowan/zulip,synicalsyntax/zulip,punchagan/zulip,jrowan/zulip,hackerkid/zulip,Galexrt/zulip,dhcrzf/zulip,timabbott/zulip,rishig/zulip,vaidap/zulip,andersk/zulip,brainwane/zulip,jackrzhang/zulip,brainwane/zulip,vabs22/zulip,jrowan/zulip,brainwane/zulip,kou/zulip,timabbott/zulip,hackerkid/zulip,eeshangarg/zulip,brockwhittaker/zulip,Galexrt/zulip,andersk/zulip,rht/zulip,vaidap/zulip,brockwhittaker/zulip,jackrzhang/zulip,mahim97/zulip,jrowan/zulip,vaidap/zulip,showell/zulip,showell/zulip,jrowan/zulip