Fix sporadic test failure in 'Test StartLearning'

[mheidinger]

Test StartLearning
  /home/max/Projects/paper-tracker/server/managers/learning_manager_test.go:84
    StartLearning inserts first command [It]
    /home/max/Projects/paper-tracker/server/managers/learning_manager_test.go:112

    Test Panicked
    runtime error: invalid memory address or nil pointer dereference
    /usr/lib/go/src/runtime/panic.go:679

    Full Stack Trace
        /home/max/go/pkg/mod/github.com/onsi/[email protected]/internal/codelocation/code_location.go:14 +0x78
    github.com/onsi/ginkgo.GinkgoRecover()
        /home/max/go/pkg/mod/github.com/onsi/[email protected]/ginkgo_dsl.go:278 +0x62
    panic(0x8a2340, 0xd758e0)
        /usr/lib/go/src/runtime/panic.go:679 +0x1b2
    paper-tracker/managers.(*TrackerManager).SetTrackerStatus(0x0, 0x1, 0xc000052702, 0x1, 0x1)
        /home/max/Projects/paper-tracker/server/managers/tracker_manager.go:62 +0x3a
    paper-tracker/managers.(*LearningManager).learningRoutine(0xc0002e1460, 0x1, 0xc0002f0690)
        /home/max/Projects/paper-tracker/server/managers/learning_manager.go:63 +0x131
    created by paper-tracker/managers.(*LearningManager).StartLearning
        /home/max/Projects/paper-tracker/server/managers/learning_manager.go:51 +0x13b