Fix crash reported by rageshake: writeToFile may throw exceptions

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/DefaultFileService.kt

@@ -83,12 +83,10 @@ internal class DefaultFileService @Inject constructor(private val context: Conte
 
                             if (elementToDecrypt != null) {
                                 Timber.v("## decrypt file")
-                                MXEncryptedAttachments.decryptAttachment(inputStream, elementToDecrypt) ?: throw IllegalStateException("Decryption error")
+                                MXEncryptedAttachments.decryptAttachment(inputStream, elementToDecrypt)
-                            } else {
+                                        ?: throw IllegalStateException("Decryption error")
-                                inputStream
                             }
-                        }
+
-                                .map { inputStream ->
                             writeToFile(inputStream, destFile)
                             destFile
                         }