Implemented snackbar telling the user that an error has occurred when fetching their schedule through FetcherActivity.kt. Also made some slight additions to the documentation

app/src/main/java/com/denizk0461/studip/sheet/ScheduleUpdateSheet.kt

@@ -2,7 +2,6 @@ package com.denizk0461.studip.sheet
 
 import android.os.Bundle
 import android.view.View
-import android.widget.TimePicker
 import androidx.fragment.app.FragmentActivity
 import com.denizk0461.studip.R
 import com.denizk0461.studip.data.parseToMinutes
@@ -11,6 +10,13 @@ import com.denizk0461.studip.databinding.SheetScheduleUpdateBinding
 import com.denizk0461.studip.dialog.TimePickerFragment
 import com.denizk0461.studip.model.StudIPEvent
 
+/**
+ * Update sheet to allow the user to edit attributes for a specific schedule event.
+ *
+ * @param event     event to be updated
+ * @param onUpdate  action to execute to update the event
+ * @param onDelete  action to execute to delete the event
+ */
 class ScheduleUpdateSheet(
     private val event: StudIPEvent,
     private val onUpdate: (event: StudIPEvent) -> Unit,
@@ -28,24 +34,37 @@ class ScheduleUpdateSheet(
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
 
+        // Set editable text fields
         binding.editTextTitle.setText(event.title)
         binding.editTextLecturers.setText(event.lecturer)
         binding.editTextRoom.setText(event.room)
 
+        // Prepare timestamp buttons
         binding.buttonTimeStart.text = timeslotStart
         binding.buttonTimeStart.setOnClickListener {
-            TimePickerFragment(binding.buttonTimeStart.text.toString(), this, true).show((context as FragmentActivity).supportFragmentManager, "timePicker")
+            TimePickerFragment(
+                binding.buttonTimeStart.text.toString(),
+                this,
+                true,
+            ).show((context as FragmentActivity).supportFragmentManager, "timePicker")
         }
         binding.buttonTimeEnd.text = timeslotEnd
         binding.buttonTimeEnd.setOnClickListener {
-            TimePickerFragment(binding.buttonTimeEnd.text.toString(), this, false).show((context as FragmentActivity).supportFragmentManager, "timePicker")
+            TimePickerFragment(
+                binding.buttonTimeEnd.text.toString(),
+                this,
+                false,
+            ).show((context as FragmentActivity).supportFragmentManager, "timePicker")
         }
 
+        // Prepare delete button
         binding.buttonDelete.setOnClickListener {
             onDelete(event)
+            // Dismiss the sheet upon deletion
             dismiss()
         }
 
+        // Prepare update/save button
         binding.buttonSave.setOnClickListener {
             onUpdate(
                 StudIPEvent(
@@ -60,22 +79,28 @@ class ScheduleUpdateSheet(
                     colour = colour,
                 )
             )
+            // Dismiss the sheet upon update
             dismiss()
         }
     }
 
     /**
+     * Checks and stores a new timestamp after the user picks one through [TimePickerFragment].
      *
+     * @param hours         newly set hour
+     * @param minutes       newly set minute
+     * @param isEventStart  whether this timestamp is for the start of the course
      */
     override fun onTimeSet(hours: Int, minutes: Int, isEventStart: Boolean) {
-
+        // Parse the separate ints into a timestamp string
         val newTimestamp = "$hours:$minutes"
 
+        // If start > end, show an error
         if ((isEventStart && newTimestamp.parseToMinutes() > timeslotEnd.parseToMinutes()) ||
             (!isEventStart && newTimestamp.parseToMinutes() < timeslotStart.parseToMinutes())) {
             // tell user that the timestamp must be set earlier/later
         } else {
-
+            // If the new timestamp is valid, save it
             if (isEventStart) {
                 timeslotStart = newTimestamp
                 binding.buttonTimeStart.text = newTimestamp