Report more errors when database is opened

moor/lib/src/runtime/executor/helpers/engines.dart

@@ -240,14 +240,26 @@ class DelegatedDatabase extends QueryExecutor with _ExecutorWithQueryDelegate {
     logStatements ??= false;
   }
 
+  var _ensureOpenCalledCounter = 0; // todo remove
+
   @override
   Future<bool> ensureOpen() {
-    return _openingLock.synchronized(() async {
+    final call = ++_ensureOpenCalledCounter;
-      final alreadyOpen = await delegate.isOpen;
+    print('ensure_open_$call: called');
-      if (alreadyOpen) return true;
 
+    return _openingLock.synchronized(() async {
+      print('ensure_open_$call: lock aquired');
+      final alreadyOpen = await delegate.isOpen;
+      if (alreadyOpen) {
+        print('ensure_open_$call: was already open');
+        return true;
+      }
+
+      print('ensure_open_$call: opening database');
       await delegate.open(databaseInfo);
+      print('ensure_open_$call: running migrations');
       await _runMigrations();
+      print('ensure_open_$call: done with opening');
       return true;
     });
   }

moor_flutter/lib/moor_flutter.dart

@@ -53,11 +53,11 @@ class _SqfliteDelegate extends DatabaseDelegate with _SqfliteExecutor {
 
   @override
   Future<void> open([GeneratedDatabase db]) async {
-    print('uses fix for the opening problem.');
     assert(
         !_debugIsOpening && !isOpen,
         'Database opened multiple times, this should never happen. '
-        'Please report this at https://github.com/simolus3/moor/issues/135 to help fix this!');
+        'Please report this at https://github.com/simolus3/moor/issues/135 to help fix this!'
+        'Db already opened: $isOpen. Other operation in progress: $_debugIsOpening');
     _debugIsOpening = true;
 
     try {