EventSystem Compileerror: use of undefined type 'std::basic_ostream<char,std::char_traits<char>>

[TerraCraftere3]

Bug when compiling

Hey, i get an error everytime i try compiling my gameengine, i am currently working on my first gameengine and watching the "GameEngine Series" and trying to get the eventsystem running, it says _use of undefined type 'std::basic_ostream<char,std::char_traits>' and things like **'iostate': undeclared identifier_**, i have a github repo called TerraCraftere3/Titan on the branch eventsystem.

[TerraCraftere3]

Also when i compile the engine it gives me no errors, but when i compile Sandbox it gives me all this errors

[VagueLobster]

Also when i compile the engine it gives me no errors, but when i compile Sandbox it gives me all this errors

You're better off asking in Cherno's Discord Server ;) You're asking for help regarding your own engine, and not little Hazel!

[TerraCraftere3]

ok, thank you @VagueLobster