Avoid crashing on start up if no active book is found

This should not happend, but it does. We've received some reports
through Crashlytics.

Nothing obviously wrong has been found. Maybe it got into an invalid
state due to some bug in a previous version. As a consequence, this just
workarounds the problem by setting the first book in the database as
active so the application doesn't crash again.

Fixes:
 http://crashes.to/s/63a0b0221ed
 http://crashes.to/s/740af90dd24
 http://crashes.to/s/e5edc6bf27e

Author: rivaldi8

app/src/main/java/org/gnucash/android/app/GnuCashApplication.java

@@ -50,6 +50,7 @@
 import org.gnucash.android.db.adapter.ScheduledActionDbAdapter;
 import org.gnucash.android.db.adapter.SplitsDbAdapter;
 import org.gnucash.android.db.adapter.TransactionsDbAdapter;
+import org.gnucash.android.model.Book;
 import org.gnucash.android.model.Commodity;
 import org.gnucash.android.model.Money;
 import org.gnucash.android.service.ScheduledActionService;
@@ -145,8 +146,14 @@ public static void initializeDatabaseAdapters() {
             mDbHelper.getReadableDatabase().close();
         }
 
-        mDbHelper = new DatabaseHelper(getAppContext(),
-                mBooksDbAdapter.getActiveBookUID());
+        try {
+            mDbHelper = new DatabaseHelper(getAppContext(),
+                                           mBooksDbAdapter.getActiveBookUID());
+        } catch (BooksDbAdapter.NoActiveBookFoundException e) {
+            fixBooksDatabase();
+            mDbHelper = new DatabaseHelper(getAppContext(),
+                                           mBooksDbAdapter.getActiveBookUID());
+        }
         SQLiteDatabase mainDb;
         try {
             mainDb = mDbHelper.getWritableDatabase();
@@ -167,6 +174,13 @@ public static void initializeDatabaseAdapters() {
         mBudgetsDbAdapter           = new BudgetsDbAdapter(mainDb, mBudgetAmountsDbAdapter, mRecurrenceDbAdapter);
     }
 
+    /** Sets the first book in the database as active. */
+    private static void fixBooksDatabase() {
+        Book firstBook = BooksDbAdapter.getInstance().getAllRecords().get(0);
+        firstBook.setActive(true);
+        BooksDbAdapter.getInstance().addRecord(firstBook);
+    }
+
     public static AccountsDbAdapter getAccountsDbAdapter() {
         return mAccountsDbAdapter;
     }

app/src/main/java/org/gnucash/android/db/adapter/BooksDbAdapter.java

@@ -156,14 +156,20 @@ public boolean isActive(String bookUID){
                 BookEntry.COLUMN_ACTIVE + "= 1", null, null, null, null, "1");
         try{
             if (cursor.getCount() == 0)
-                throw new RuntimeException("There is no active book in the app. This should NEVER happen, fix your bugs!");
+                throw new NoActiveBookFoundException("There is no active book in the app. This should NEVER happen, fix your bugs!");
             cursor.moveToFirst();
             return cursor.getString(cursor.getColumnIndexOrThrow(BookEntry.COLUMN_UID));
         } finally {
             cursor.close();
         }
     }
 
+    public class NoActiveBookFoundException extends RuntimeException {
+        public NoActiveBookFoundException(String message) {
+            super(message);
+        }
+    }
+
     public @NonNull List<String> getAllBookUIDs(){
         List<String> bookUIDs = new ArrayList<>();
         try (Cursor cursor = mDb.query(true, mTableName, new String[]{BookEntry.COLUMN_UID},