portico: Fix overlap of server and frontend errors.
portico: Fix overlap of server and frontend errors.

Clears the errors received from the server whenever there is a chance of
overlap among them.

Fixes #10831.

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