https://www.wowhead.com/spell=285440/hidden-flame-cannon

Looks like the code isn't handling names that contain " characters, probably need to delimit this with a backslash so the whole name string is valid:

spells = { [285440] = { name = ""Hidden" Flame Cannon", important = 0, deadly = 0, avoidable = 0, heavy_fail_dps = 0, heavy_fail_healer = 0, heavy_fail_tank = 0, interruptible = 0, countermeasures = [=[]=], },

Actual error is:

Wowop.io/database_dungeons.lua:1 Wowop.io/database_dungeons.lua:13873: '}' expected (to close '{' at line 13872) near 'Hidden'