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>
diff --git a/desktop/source/minidump/minidump_upload.cxx b/desktop/source/minidump/minidump_upload.cxx
index 3f17c04..30eaaaa 100644
--- a/desktop/source/minidump/minidump_upload.cxx
+++ b/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.