[Xiaomi Mi A1 ROMs, Kernels, Recoveries, & Other De] eatsfoobars:
I have a relevant logcat:

12-25 16:29:00.524 28839 28839 E System : ******************************************
12-25 16:29:00.525 28839 28839 E System : ************ Failure starting system services
12-25 16:29:00.525 28839 28839 E System : java.lang.RuntimeException: There must be exactly one installer; found []
12-25 16:29:00.525 28839 28839 E System : at com.android.server.pm.PackageManagerService.getRequiredInstallerLPr(PackageManagerService.java:8318)
12-25 16:29:00.525 28839 28839 E System : at com.android.server.pm.PackageManagerService.<init>(PackageManagerService.java:7790)
12-25 16:29:00.525 28839 28839 E System : at com.android.server.pm.PackageManagerService.main(PackageManagerService.java:6772)
12-25 16:29:00.525 28839 28839 E System : at com.android.server.SystemServer.startBootstrapServices(SystemServer.java:1163)
12-25 16:29:00.525 28839 28839 E System : at com.android.server.SystemServer.run(SystemServer.java:877)
12-25 16:29:00.525 28839 28839 E System : at com.android.server.SystemServer.main(SystemServer.java:610)
12-25 16:29:00.525 28839 28839 E System : at java.lang.reflect.Method.invoke(Native Method)
12-25 16:29:00.525 28839 28839 E System : at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
12-25 16:29:00.525 28839 28839 E System : at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:981)
12-25 16:29:00.525 28839 28839 E Zygote : System zygote died with fatal exception
12-25 16:29:00.525 28839 28839 E Zygote : java.lang.RuntimeException: There must be exactly one installer; found []
12-25 16:29:00.525 28839 28839 E Zygote : at com.android.server.pm.PackageManagerService.getRequiredInstallerLPr(PackageManagerService.java:8318)
12-25 16:29:00.525 28839 28839 E Zygote : at com.android.server.pm.PackageManagerService.<init>(PackageManagerService.java:7790)
12-25 16:29:00.525 28839 28839 E Zygote : at com.android.server.pm.PackageManagerService.main(PackageManagerService.java:6772)
12-25 16:29:00.525 28839 28839 E Zygote : at com.android.server.SystemServer.startBootstrapServices(SystemServer.java:1163)
12-25 16:29:00.525 28839 28839 E Zygote : at com.android.server.SystemServer.run(SystemServer.java:877)
12-25 16:29:00.525 28839 28839 E Zygote : at com.android.server.SystemServer.main(SystemServer.java:610)
12-25 16:29:00.525 28839 28839 E Zygote : at java.lang.reflect.Method.invoke(Native Method)
12-25 16:29:00.525 28839 28839 E Zygote : at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
12-25 16:29:00.525 28839 28839 E Zygote : at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:981)
12-25 16:29:00.525 28839 28839 D AndroidRuntime: Shutting down VM
12-25 16:29:00.525 28839 28839 E AndroidRuntime: *** FATAL EXCEPTION IN SYSTEM PROCESS: main
12-25 16:29:00.525 28839 28839 E AndroidRuntime: java.lang.RuntimeException: There must be exactly one installer; found []
12-25 16:29:00.525 28839 28839 E AndroidRuntime: at com.android.server.pm.PackageManagerService.getRequiredInstallerLPr(PackageManagerService.java:8318)
12-25 16:29:00.525 28839 28839 E AndroidRuntime: at com.android.server.pm.PackageManagerService.<init>(PackageManagerService.java:7790)
12-25 16:29:00.525 28839 28839 E AndroidRuntime: at com.android.server.pm.PackageManagerService.main(PackageManagerService.java:6772)
12-25 16:29:00.525 28839 28839 E AndroidRuntime: at com.android.server.SystemServer.startBootstrapServices(SystemServer.java:1163)
12-25 16:29:00.525 28839 28839 E AndroidRuntime: at com.android.server.SystemServer.run(SystemServer.java:877)
12-25 16:29:00.525 28839 28839 E AndroidRuntime: at com.android.server.SystemServer.main(SystemServer.java:610)
12-25 16:29:00.525 28839 28839 E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
12-25 16:29:00.525 28839 28839 E AndroidRuntime: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
12-25 16:29:00.525 28839 28839 E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:981)
12-25 16:29:00.527 28839 28839 E AndroidRuntime: Error reporting crash
12-25 16:29:00.527 28839 28839 E AndroidRuntime: java.lang.NullPointerException: Attempt to invoke interface method 'void android.app.IActivityManager.handleApplicationCrash(android.os.IBinder, android.app.ApplicationErrorReport$ParcelableCrashInfo)' on a null object reference
12-25 16:29:00.527 28839 28839 E AndroidRuntime: at com.android.internal.os.RuntimeInit$KillApplicationHandler.uncaughtException(RuntimeInit.java:156)
12-25 16:29:00.527 28839 28839 E AndroidRuntime: at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:1073)
12-25 16:29:00.527 28839 28839 E AndroidRuntime: at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:1068)
12-25 16:29:00.527 28839 28839 E AndroidRuntime: at java.lang.Thread.dispatchUncaughtException(Thread.java:2200)
12-25 16:29:00.527 28839 28839 I Process : Sending signal. PID: 28839 SIG: 9
12-25 16:29:00.609 28695 28695 E Zygote : Zygote failed to write to system_server FD: Connection refused
12-25 16:29:00.609 28695 28695 I Zygote : Process 28839 exited due to signal 9 (Killed)
12-25 16:29:00.609 28695 28695 E Zygote : Exit zygote because system server (pid 28839) has terminated