Merge pull request #314 from plukkido/master

Fixing #236 which did not expect null from DownloadManager.query()

android/src/main/java/com/RNFetchBlob/RNFetchBlobReq.java

                 DownloadManager dm = (DownloadManager) appCtx.getSystemService(Context.DOWNLOAD_SERVICE);
                 dm.query(query);
                 Cursor c = dm.query(query);
-
+                // #236 unhandled null check for DownloadManager.query() return value
+                if (c == null) {
+                    this.callback.invoke("Download manager failed to download from  " + this.url + ". Query was unsuccessful ", null, null);
+                    return;
+                }
 
                 String filePath = null;
-                // the file exists in media content database
-                if (c.moveToFirst()) {
-                    // #297 handle failed request
-                    int statusCode = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));
-                    if(statusCode == DownloadManager.STATUS_FAILED) {
-                        this.callback.invoke("Download manager failed to download from  " + this.url + ". Status Code = " + statusCode, null, null);
-                        return;
-                    }
-                    String contentUri = c.getString(c.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));
-                    if ( contentUri != null &&
-                            options.addAndroidDownloads.hasKey("mime") &&
-                            options.addAndroidDownloads.getString("mime").contains("image")) {
-                        Uri uri = Uri.parse(contentUri);
-                        Cursor cursor = appCtx.getContentResolver().query(uri, new String[]{android.provider.MediaStore.Images.ImageColumns.DATA}, null, null, null);
-                        // use default destination of DownloadManager
-                        if (cursor != null) {
-                            cursor.moveToFirst();
-                            filePath = cursor.getString(0);
-                            cursor.close();
+                try {    
+                    // the file exists in media content database
+                    if (c.moveToFirst()) {
+                        // #297 handle failed request
+                        int statusCode = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));
+                        if(statusCode == DownloadManager.STATUS_FAILED) {
+                            this.callback.invoke("Download manager failed to download from  " + this.url + ". Status Code = " + statusCode, null, null);
+                            return;
+                        }
+                        String contentUri = c.getString(c.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));
+                        if ( contentUri != null &&
+                                options.addAndroidDownloads.hasKey("mime") &&
+                                options.addAndroidDownloads.getString("mime").contains("image")) {
+                            Uri uri = Uri.parse(contentUri);
+                            Cursor cursor = appCtx.getContentResolver().query(uri, new String[]{android.provider.MediaStore.Images.ImageColumns.DATA}, null, null, null);
+                            // use default destination of DownloadManager
+                            if (cursor != null) {
+                                cursor.moveToFirst();
+                                filePath = cursor.getString(0);
+                                cursor.close();
+                            }
                         }
                     }
+                } finally {
+                    if (c != null) {
+                        c.close();
+                    }
                 }
 
                 // When the file is not found in media content database, check if custom path exists