add some more error checking to minidump uploader

Change-Id: Ia06fec80ea67e88b8c26cdeb5bfc9cee2459ad4a
Reviewed-on: https://gerrit.libreoffice.org/25861
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>

desktop/source/minidump/minidump_upload.cxx

@@ -100,6 +100,12 @@ bool uploadContent(std::map<std::string, std::string>& parameters)
     if (url.empty())
         return false;
 
+    if (file.empty())
+        return false;
+
+    if (version.empty())
+        return false;
+
     curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
     curl_easy_setopt(curl, CURLOPT_USERAGENT, kUserAgent);
     // Set proxy information if necessary.