The app is crashing when RegisterActivity is started

[grig-guz]

When I hit "Don't have an account yet?", the app crashes. This is the error message that I get:
6-16 19:49:36.843 7301-7301/com.android.ubclaunchpad.driver E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.android.ubclaunchpad.driver, PID: 7301
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at com.google.android.gms.internal.zzaix$zza.zzaE(Unknown Source)
at com.google.android.gms.internal.zzaix.zzaw(Unknown Source)
at com.google.android.gms.internal.zzaix.zzav(Unknown Source)
at com.google.firebase.database.DatabaseReference.zza(Unknown Source)
at com.google.firebase.database.DatabaseReference.setValue(Unknown Source)
at com.android.ubclaunchpad.driver.UI.RegisterActivity$1.onAuthStateChanged(RegisterActivity.java:66)
at com.google.firebase.auth.FirebaseAuth$1.run(Unknown Source)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at com.google.android.gms.internal.zzaix$zza.zzaE(Unknown Source) 
at com.google.android.gms.internal.zzaix.zzaw(Unknown Source) 
at com.google.android.gms.internal.zzaix.zzav(Unknown Source) 
at com.google.firebase.database.DatabaseReference.zza(Unknown Source) 
at com.google.firebase.database.DatabaseReference.setValue(Unknown Source) 
at com.android.ubclaunchpad.driver.UI.RegisterActivity$1.onAuthStateChanged(RegisterActivity.java:66) 
at com.google.firebase.auth.FirebaseAuth$1.run(Unknown Source) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6119) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.Integer.intValue()' on a null object reference
at com.android.ubclaunchpad.driver.models.User.getNumFreeSeats(User.java:65)
at java.lang.reflect.Method.invoke(Native Method) 
at com.google.android.gms.internal.zzaix$zza.zzaE(Unknown Source) 
at com.google.android.gms.internal.zzaix.zzaw(Unknown Source) 
at com.google.android.gms.internal.zzaix.zzav(Unknown Source) 
at com.google.firebase.database.DatabaseReference.zza(Unknown Source) 
at com.google.firebase.database.DatabaseReference.setValue(Unknown Source) 
at com.android.ubclaunchpad.driver.UI.RegisterActivity$1.onAuthStateChanged(RegisterActivity.java:66) 
at com.google.firebase.auth.FirebaseAuth$1.run(Unknown Source) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6119) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
06-16 19:49:43.896 7301-7319/com.android.ubclaunchpad.driver E/DynamiteModule: Failed to load module descriptor class: Didn't find class "com.google.android.gms.dynamite.descriptors.com.google.firebase.auth.ModuleDescriptor" on path: DexPathList[[zip file "/data/app/com.android.ubclaunchpad.driver-1/base.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_dependencies_apk.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_slice_0_apk.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_slice_1_apk.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_slice_2_apk.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_slice_3_apk.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_slice_4_apk.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_slice_5_apk.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_slice_6_apk.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_slice_7_apk.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_slice_8_apk.apk", zip file "/data/app/com.android.ubclaunchpad.driver-1/split_lib_slice_9_apk.apk"],nativeLibraryDirectories=[/data/app/com.android.ubclaunchpad.driver-1/lib/x86_64, /system/lib64, /vendor/lib64]]