Description:
When trying to open a document (LibreOffice or MS-Office doesn't matter) via a WebDAV-request initiated by an Active-X plugin LibreOffice crashes when the servers submits an xml-formatted error. 

Steps to Reproduce:
Example communications (this happens after succesfully downloading the file):
```
HTTP/1.1 423 Locked
Server: Apache-Coyote/1.1
Set-Cookie: JSESSIONID=F6CB0E0333AF3380249D60F31B1A7E37; Path=/visj-web-app; HttpOnly
Engine: IT Hit WebDAV Server
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
Access-Control-Allow-Methods: PROPFIND, PROPPATCH, COPY, MOVE, DELETE, MKCOL, LOCK, UNLOCK, PUT, GETLIB, VERSION-CONTROL, CHECKIN, CHECKOUT, UNCHECKOUT, REPORT, UPDATE, CANCELUPLOAD, HEAD, OPTIONS, GET, POST
Access-Control-Allow-Headers: Overwrite, Destination, Content-Type, Depth, User-Agent, X-File-Size, X-Requested-With, If-Modified-Since, X-File-Name, Cache-Control
Access-Control-Max-Age: 2147483647
Content-Type: text/xml;charset=UTF-8
Date: Mon, 29 Jul 2019 11:08:20 GMT
Content-Length: 125

<?xml version="1.0" ?><d:error xmlns:d="DAV:"><d:responsedescription>The object is readonly</d:responsedescription></d:error>
```
or 
```
HTTP/1.1 500 Internal Server Error
Server: Apache-Coyote/1.1
Set-Cookie: JSESSIONID=E32CCE9A51437250DC936EFDCBF9475D; Path=/visj-web-app; HttpOnly
Engine: IT Hit WebDAV Server
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
Access-Control-Allow-Methods: PROPFIND, PROPPATCH, COPY, MOVE, DELETE, MKCOL, LOCK, UNLOCK, PUT, GETLIB, VERSION-CONTROL, CHECKIN, CHECKOUT, UNCHECKOUT, REPORT, UPDATE, CANCELUPLOAD, HEAD, OPTIONS, GET, POST
Access-Control-Allow-Headers: Overwrite, Destination, Content-Type, Depth, User-Agent, X-File-Size, X-Requested-With, If-Modified-Since, X-File-Name, Cache-Control
Access-Control-Max-Age: 2147483647
Content-Type: text/xml;charset=UTF-8
Date: Mon, 29 Jul 2019 09:54:44 GMT
Connection: close
Content-Length: 664

<?xml version="1.0" ?><d:error xmlns:d="DAV:"><d:responsedescription>javax.xml.stream.XMLStreamException: NamespaceURI pdv has not been bound to any prefix</d:responsedescription></d:error><?xml version="1.0" ?><d:multistatus xmlns:d="DAV:"><d:response><d:href>http://localhost:8080/server-endpoint/webdav/12/Example_file.docx</d:href><d:propstat><d:status>HTTP/1.1 200 OK</d:status><d:prop><d:getcontentlength/><d:getcontenttype/><d:displayname/><d:resourcetype/><d:creationdate/><d:getlastmodified/><d:supportedlock/><d:lockdiscovery/><d:supported-live-property-set/><d:supported-method-set/><d:supported-report-set/><
```

Connected incident reports are:
- http://crashreport.libreoffice.org/stats/crash_details/631653fd-9ad2-4e1e-9507-5113092515e3
- http://crashreport.libreoffice.org/stats/crash_details/5a25b642-a290-4097-8ba7-d8b21aba7899
http://crashreport.libreoffice.org/stats/crash_details/8eb6b2be-cc21-4a13-842e-783627392072
http://crashreport.libreoffice.org/stats/crash_details/631653fd-9ad2-4e1e-9507-5113092515e3

We workaround the bug by downloading the file first and then opening it.

Actual Results:
LibreOffice crashes.

Expected Results:
Document should open (indicating it's readonly if necessary)


Reproducible: Always


User Profile Reset: Yes



Additional Info: