I ran just Forgelin and BetterPortals and Minecraft will not open, crashing after loading. Here is the crash report:

---- Minecraft Crash Report ----

WARNING: coremods are present:
ForgelinPlugin (Forgelin-1.8.4.jar)
Contact their authors BEFORE contacting forge

// You should try our sister game, Minceraft!

Time: 11/17/19 1:01 PM
Description: Initializing game

java.lang.NoClassDefFoundError: net/minecraft/client/renderer/EntityRenderer
at net.minecraftforge.client.ForgeHooksClient.shouldUseVanillaReloadableListener(ForgeHooksClient.java:777)
at net.minecraft.client.resources.SimpleReloadableResourceManager.func_110544_b(SimpleReloadableResourceManager.java:131)
at net.minecraft.client.resources.SimpleReloadableResourceManager.func_110541_a(SimpleReloadableResourceManager.java:112)
at net.minecraft.client.Minecraft.func_110436_a(Minecraft.java:807)
at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:247)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:466)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377)
at net.minecraft.client.main.Main.main(SourceFile:123)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.ClassNotFoundException: net.minecraft.client.renderer.EntityRenderer
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:101)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 14 more

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Head --
Thread: Client thread
Stacktrace:
at net.minecraftforge.client.ForgeHooksClient.shouldUseVanillaReloadableListener(ForgeHooksClient.java:777)
at net.minecraft.client.resources.SimpleReloadableResourceManager.func_110544_b(SimpleReloadableResourceManager.java:131)
at net.minecraft.client.resources.SimpleReloadableResourceManager.func_110541_a(SimpleReloadableResourceManager.java:112)
at net.minecraft.client.Minecraft.func_110436_a(Minecraft.java:807)
at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:247)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:466)

-- Initialization --
Details:
Stacktrace:
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377)
at net.minecraft.client.main.Main.main(SourceFile:123)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

-- System Details --
Details:
Minecraft Version: 1.12.2
Operating System: Mac OS X (x86_64) version 10.15
Java Version: 1.8.0_74, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 180779608 bytes (172 MB) / 402653184 bytes (384 MB) up to 2147483648 bytes (2048 MB)
JVM Flags: 7 total; -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML: MCP 9.42 Powered by Forge 14.23.5.2768 6 mods loaded, 6 mods active
States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

State	ID	Version	Source	Signature
UC	minecraft	1.12.2	minecraft.jar	None
UC	mcp	9.42	minecraft.jar	None
UC	FML	8.0.99.99	forge-1.12.2-14.23.5.2768.jar	e3c3d50c7c986df74c645c0ac54639741c90a557
UC	forge	14.23.5.2768	forge-1.12.2-14.23.5.2768.jar	e3c3d50c7c986df74c645c0ac54639741c90a557
UC	forgelin	1.8.4	Forgelin-1.8.4.jar	None
U	betterportals	0.3.7.1	betterportals-0.3.7.1.jar	None

Loaded coremods (and transformers):
ForgelinPlugin (Forgelin-1.8.4.jar)

GL info: ' Vendor: 'Intel Inc.' Version: '2.1 INTEL-14.0.67' Renderer: 'Intel(R) HD Graphics 6000'
Launched Version: 1.12.2-forge1.12.2-14.23.5.2768
LWJGL: 2.9.2
OpenGL: Intel(R) HD Graphics 6000 GL version 2.1 INTEL-14.0.67, Intel Inc.
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because ARB_framebuffer_object is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: Yes
Is Modded: Definitely; Client brand changed to 'fml,forge'
Type: Client (map_client.txt)
Resource Packs: Faithful 1.12.2.zip
Current Language: ERROR NullPointerException: null
Profiler Position: N/A (disabled)
CPU: 4x Intel(R) Core(TM) i5-5250U CPU @ 1.60GHz

I finally got it to work by running Forgelin alone, closing Minecraft and then running BetterPortals with Forgelin. The next time I closed Minecraft and tried to reopen it, it crashed again with the same errors

Please attach the full game log. There's likely a more direct hint on the issue in it, the crash report itself unfortunately doesn't tell much in this case.