zjquery: Give clear error when handlers are not set.
zjquery: Give clear error when handlers are not set.

jackrzhang/zulip,timabbott/zulip,shubhamdhama/zulip,hackerkid/zulip,punchagan/zulip,shubhamdhama/zulip,rishig/zulip,brainwane/zulip,dhcrzf/zulip,brainwane/zulip,dhcrzf/zulip,synicalsyntax/zulip,rishig/zulip,rht/zulip,eeshangarg/zulip,eeshangarg/zulip,punchagan/zulip,hackerkid/zulip,eeshangarg/zulip,shubhamdhama/zulip,tommyip/zulip,jackrzhang/zulip,eeshangarg/zulip,eeshangarg/zulip,rishig/zulip,kou/zulip,timabbott/zulip,kou/zulip,showell/zulip,rht/zulip,zulip/zulip,jackrzhang/zulip,andersk/zulip,showell/zulip,showell/zulip,brainwane/zulip,kou/zulip,timabbott/zulip,dhcrzf/zulip,hackerkid/zulip,kou/zulip,tommyip/zulip,brainwane/zulip,synicalsyntax/zulip,tommyip/zulip,synicalsyntax/zulip,tommyip/zulip,tommyip/zulip,rishig/zulip,timabbott/zulip,showell/zulip,andersk/zulip,andersk/zulip,punchagan/zulip,andersk/zulip,rht/zulip,timabbott/zulip,jackrzhang/zulip,eeshangarg/zulip,shubhamdhama/zulip,jackrzhang/zulip,zulip/zulip,dhcrzf/zulip,tommyip/zulip,punchagan/zulip,punchagan/zulip,andersk/zulip,synicalsyntax/zulip,rht/zulip,hackerkid/zulip,showell/zulip,dhcrzf/zulip,jackrzhang/zulip,timabbott/zulip,andersk/zulip,showell/zulip,kou/zulip,zulip/zulip,hackerkid/zulip,kou/zulip,hackerkid/zulip,punchagan/zulip,punchagan/zulip,timabbott/zulip,zulip/zulip,synicalsyntax/zulip,rht/zulip,zulip/zulip,kou/zulip,showell/zulip,synicalsyntax/zulip,synicalsyntax/zulip,dhcrzf/zulip,rht/zulip,rishig/zulip,andersk/zulip,brainwane/zulip,tommyip/zulip,dhcrzf/zulip,brainwane/zulip,rishig/zulip,zulip/zulip,hackerkid/zulip,rishig/zulip,rht/zulip,jackrzhang/zulip,eeshangarg/zulip,shubhamdhama/zulip,shubhamdhama/zulip,shubhamdhama/zulip,zulip/zulip,brainwane/zulip