Attempt to use the "Generate" function over the `docx` document from the pipeline DOCUMENTS tab throws an error

**Describe the bug**
When trying to use the "Generate" function over the `docx` document from the pipeline DOCUMENTS tab - two files are downloaded to the local machine, both with the same name, one file is the same as the original `docx` document and the second contains only the error instead of the document content

**To Reproduce**
Steps to reproduce the behavior:
1. Open any pipeline, select the DOCUMENTS tab
2. Upload the document with `docx` extension
3. Click the **Generate** button next to the uploaded document
4. Wait until files will be downloaded
5. Open the smaller file in any text editor
6. See the error: `{"message":"Error while executing command python /usr/lib/python2.7/site-packages/scripts/deps_graph.py /opt/api/workspace/git7009710166274989972 config.json: \nTraceback (most recent call last):\n File \"/usr/lib/python2.7/site-packages/scripts/deps_graph.py\", line 108, in \n main_file, main_class = parse_config(config, config_name)\n File \"/usr/lib/python2.7/site-packages/scripts/deps_graph.py\", line 91, in parse_config\n return get_main_file_class(item['configuration'])\n File \"/usr/lib/python2.7/site-packages/scripts/deps_graph.py\", line 96, in get_main_file_class\n return config['main_file'][:-3], config['main_class']\nKeyError: 'main_file'","status":"ERROR"}`

**Expected behavior**
More convenient and clear error message

**Environment:**
- Cloud Provider: N/A
- Version: 0.16.0.3326.baa436998d5541afca887e14746c1db3bc8bcd39
- Browser: chrome, Mozilla Firefox, MS Edge