lightbox: Fix incorrect use of const and typo.
lightbox: Fix incorrect use of const and typo.

This was a bug in 1d3827d518949a09f2e4fc03c4327d8ee536e6f8.

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