[OnePlus 5 Themes, Apps, and Mods] sawxda:
First of all, thank you @Urnyx05 for working on the package!

On the subject: I confirm that entering the slow motion mode leads to a fatal error in the app—tried on OP6 with a freshly installed LiquidRemix.

The relevant portion of the log looks as follows:

D CAM_CameraActivity: Closing v1 Camera before using mode SLOW_MOTION
V CAM_CameraController: Closing camera
W CAM2PORT_AndCamAgntImp: Releasing camera without any camera opened.
I CAM_SimpleModuleAgent: Creating module: VideoHfrModule
I chatty : uid=10176(com.google.android.GoogleCamera) identical 2 lines
I CAM_CdrCharacteristics: checkResolutionListOrder: [FPS_120_HFR_4X] = []
I CAM_CdrCharacteristics: checkResolutionListOrder: [FPS_AUTO] = [RES_1080P, RES_720P, RES_480P, RES_CIF, RES_QVGA, RES_QCIF]
I CAM_CdrCharacteristics: checkResolutionListOrder: [FPS_30] = [RES_1080P, RES_720P, RES_480P, RES_CIF, RES_QVGA, RES_QCIF]
I CAM_CdrCharacteristics: checkResolutionListOrder: [FPS_60_HFR_2X] = []
I CAM_CdrCharacteristics: checkResolutionListOrder: [FPS_60] = [RES_1080P, RES_720P, RES_480P, RES_CIF, RES_QVGA, RES_QCIF]
I CAM_CdrCharacteristics: checkResolutionListOrder: [FPS_240_HFR_8X] = []
I chatty : uid=10176(com.google.android.GoogleCamera) identical 1 line
E BufferQueueProducer: [SurfaceView - com.google.android.GoogleCamera/com.android.camera.CameraLauncher#0] queueBuffer: BufferQueue has been abandoned
E Surface : queueBuffer: error queuing buffer to SurfaceTexture, -19
E Camera3-OutputStream: returnBufferCheckedLocked: Stream 0: Error queueing buffer to native window: No such device (-19)
E Camera3-Device: Can't return buffer to its stream: No such device (-19)
E BufferQueueProducer: [SurfaceView - com.google.android.GoogleCamera/com.android.camera.CameraLauncher#0] dequeueBuffer: BufferQueue has been abandoned
E Camera3-OutputStream: getBufferLockedCommon: Stream 0: Can't dequeue next output buffer: No such device (-19)
E Camera3-Device: RequestThread: Can't get output buffer, skipping request: No such device (-19)
D CAM_CdrFastVid2Mod: New instance created.
D CAM_CdrFastVid2Mod: state updated from null to UNINITED
D CAM_CdrFastVid2Mod: init state=UNINITED
D CAM_CdrFastVid2Mod: state updated from UNINITED to BACKGROUND
D CAM_CdrFastVid2Mod: start state=BACKGROUND
V CAM_CameraAppUI: Switching PreviewContentImpl SURFACE_VIEW to SURFACE_VIEW
D CAM_CdrFastVid2Mod: openCamcorderDevice
D CAM_CdrFastVid2Mod: state updated from BACKGROUND to OPENING_CAMCORDER
D CAM_CdrSlowMoDevOp: openCamcorderDevice
D AndroidRuntime: Shutting down VM
E AndroidRuntime: FATAL EXCEPTION: main
E AndroidRuntime: Process: com.google.android.GoogleCamera, PID: 3967
E AndroidRuntime: java.lang.IllegalStateException
E AndroidRuntime: at mhf.b(Unknown Source:4)
E AndroidRuntime: at bsc.a(Unknown Source:330)
E AndroidRuntime: at dvz.a(Unknown Source:154)
E AndroidRuntime: at dww.a(Unknown Source:38)
E AndroidRuntime: at dww.h_(Unknown Source:106)
E AndroidRuntime: at czw.a(Unknown Source:10)
E AndroidRuntime: at daq.onSuccess(Unknown Source:80)
E AndroidRuntime: at ndf.run(Unknown Source:8)
E AndroidRuntime: at android.os.Handler.handleCallback(Handler.java:873)
E AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:99)
E AndroidRuntime: at android.os.Looper.loop(Looper.java:193)
E AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:6739)
E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
E AndroidRuntime: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:495)
E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:859)

If there are any problems with reproducing the issue, I'd be happy to help.