Ensure failsafe session can still be opened if files directory is not…

… accessible and fix comment

The `/data/data/com.termux` directory will not be created if it did not already exist and android did not already create it instead of as mentioned in 6fa4b9b. Check #2168 (comment)

app/src/main/java/com/termux/app/TermuxInstaller.java

@@ -58,8 +58,8 @@ static void setupBootstrapIfNeeded(final Activity activity, final Runnable whenD
         String bootstrapErrorMessage;
         Error filesDirectoryAccessibleError;
 
-        // This will also call Context.getFilesDir(), which should ensure that TERMUX_INTERNAL_PRIVATE_APP_DATA_DIR_PATH
-        // is created if it does not already exist, like if it was not already created by android
+        // This will also call Context.getFilesDir(), which should ensure that TERMUX_FILES_DIR_PATH
+        // is created if it does not already exist
         filesDirectoryAccessibleError = TermuxFileUtils.isTermuxFilesDirectoryAccessible(activity, true, true);
         boolean isFilesDirectoryAccessible = filesDirectoryAccessibleError == null;
 
@@ -79,9 +79,9 @@ static void setupBootstrapIfNeeded(final Activity activity, final Runnable whenD
             bootstrapErrorMessage = Error.getMinimalErrorString(filesDirectoryAccessibleError) + "\nTERMUX_FILES_DIR: " + MarkdownUtils.getMarkdownCodeForString(TermuxConstants.TERMUX_FILES_DIR_PATH, false);
             Logger.logError(LOG_TAG, bootstrapErrorMessage);
             CrashUtils.sendCrashReportNotification(activity, LOG_TAG, "## Bootstrap Error\n\n" + bootstrapErrorMessage, true, true);
-            MessageDialogUtils.exitAppWithErrorMessage(activity,
+            MessageDialogUtils.showMessage(activity,
                 activity.getString(R.string.bootstrap_error_title),
-                bootstrapErrorMessage);
+                bootstrapErrorMessage, null);
             return;
         }
 

termux-shared/src/main/java/com/termux/shared/file/TermuxFileUtils.java

@@ -128,8 +128,13 @@ public static Error validateDirectoryFileExistenceAndPermissions(String label, f
      * Validate the existence and permissions of {@link TermuxConstants#TERMUX_FILES_DIR_PATH}.
      *
      * The directory will not be created manually but by calling {@link Context#getFilesDir()}
-     * so that android itself creates it. The `/data/data/[package_name]` directory cannot be
-     * created by an app itself. Note that the path returned by {@link Context#getFilesDir()} will
+     * so that android itself creates it. However, the call will not create its parent package
+     * data directory `/data/user/0/[package_name]` if it does not already exist and a `logcat`
+     * error will be logged by android.
+     * {@code Failed to ensure /data/user/0/<package_name>/files: mkdir failed: ENOENT (No such file or directory)}
+     * An android app likely can't create the package data directory since its parent `/data/user/0`
+     * is owned by `system` user and is normally create at app install or update time and not at app startup.
+     * Note that the path returned by {@link Context#getFilesDir()} will
      * be under `/data/user/[id]/[package_name]` instead of `/data/data/[package_name]`
      * defined by default by {@link TermuxConstants#TERMUX_FILES_DIR_PATH}, where id will be 0 for
      * primary user and a higher number for other users/profiles. If app is running under work profile