I have been told to update forge. I have done so and still have the same error. I am running forge 1.12.2 with only the better portals mod in the mods folder. The crash report is attached, just in case it's different.
crash-2019-10-11_14.18.18-client.txt
P.S. What happens is the forge loading screen appears for about a second, then it crashes.

You're missing forgelin, BP depends on it. Install it and you'll be good to go.

^

You're also using an old version of BP, any version after 0.3.3 even explicitly tells you when you're missing Forgelin.