Fix oppia#5451 : java.lang.IllegalStateException - Media player has n…

…ot been previously initialized (oppia#5475)

<!-- READ ME FIRST: Please fill in the explanation section below and
check off every point from the Essential Checklist! -->
## Explanation
Fixes oppia#5451 

The error occurs if the release is attempted before the MediaPlayer is
initialized or if releaseMediaPlayer() is called multiple times. To
address this, I have modified releaseMediaPlayer() to only release the
MediaPlayer if it has not already been released. These changes properly
handle the situation when releaseMediaPlayer() is called before
initialization.
  

## Essential Checklist
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- [x] The PR title and explanation each start with "Fix #bugnum: " (If
this PR fixes part of an issue, prefix the title with "Fix part of
#bugnum: ...".)
- [ ] Any changes to
[scripts/assets](https://github.com/oppia/oppia-android/tree/develop/scripts/assets)
files have their rationale included in the PR explanation.
- [x] The PR follows the [style
guide](https://github.com/oppia/oppia-android/wiki/Coding-style-guide).
- [x] The PR does not contain any unnecessary code changes from Android
Studio
([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#undo-unnecessary-changes)).
- [x] The PR is made from a branch that's **not** called "develop" and
is up-to-date with "develop".
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([reference](https://github.com/oppia/oppia-android/wiki/Guidance-on-submitting-a-PR#clarification-regarding-assignees-and-reviewers-section)).

## For UI-specific PRs only
<!-- Delete these section if this PR does not include UI-related
changes. -->
If your PR includes UI-related changes, then:
- Add screenshots for portrait/landscape for both a tablet & phone of
the before & after UI changes
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(RTL) screenshots (see [RTL
guide](https://github.com/oppia/oppia-android/wiki/RTL-Guidelines))
- Add a video showing the full UX flow with a screen reader enabled (see
[accessibility
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---------

Co-authored-by: Adhiambo Peres <59600948+adhiamboperes@users.noreply.github.com>

domain/src/main/java/org/oppia/android/domain/audio/AudioPlayerController.kt

@@ -251,13 +251,15 @@ class AudioPlayerController @Inject constructor(
    */
   fun releaseMediaPlayer() {
     audioLock.withLock {
-      check(mediaPlayerActive) { "Media player has not been previously initialized" }
-      mediaPlayerActive = false
-      isReleased = true
-      prepared = false
-      mediaPlayer.release()
-      stopUpdatingSeekBar()
-      playProgress = null
+      if (!isReleased) {
+        check(mediaPlayerActive) { "Media player has not been previously initialized" }
+        mediaPlayerActive = false
+        isReleased = true
+        prepared = false
+        mediaPlayer.release()
+        stopUpdatingSeekBar()
+        playProgress = null
+      }
     }
   }
 

domain/src/test/java/org/oppia/android/domain/audio/AudioPlayerControllerTest.kt

@@ -11,6 +11,7 @@ import dagger.BindsInstance
 import dagger.Component
 import dagger.Module
 import dagger.Provides
+import org.junit.Assert.fail
 import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
@@ -443,6 +444,17 @@ class AudioPlayerControllerTest {
       .contains("Media player has not been previously initialized")
   }
 
+  @Test
+  fun testController_releasePlayerMultipleTimes_doesNoThrowException() {
+    setUpMediaReadyApplication()
+    audioPlayerController.initializeMediaPlayer()
+
+    assertNoExceptionIsThrown {
+      audioPlayerController.releaseMediaPlayer()
+      audioPlayerController.releaseMediaPlayer()
+    }
+  }
+
   @Test
   fun testError_notPrepared_invokePlay_fails() {
     setUpMediaReadyApplication()
@@ -872,6 +884,14 @@ class AudioPlayerControllerTest {
     ApplicationProvider.getApplicationContext<TestApplication>().inject(this)
   }
 
+  private fun assertNoExceptionIsThrown(block: () -> Unit) {
+    try {
+      block()
+    } catch (e: Exception) {
+      fail("Expected no exception, but got: $e")
+    }
+  }
+
   // TODO(#89): Move this to a common test application component.
   @Module
   class TestModule {