tdf#164686: handle exceptions from UCBContentHelper::Exists

When a filename can be treated as a non-file URL, checking its existence
may throw. This needs to be handled here.

Handles '?' in the filename.

Change-Id: If065c483d1a44cbbfcea21f91d72adf1fdfde579
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/180199
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

fpicker/source/office/iodlg.cxx

@@ -833,7 +833,18 @@ void SvtFileDialog::OpenHdl_Impl(void const * pVoid)
     {
         case FILEDLG_MODE_SAVE:
         {
-            if ( ::utl::UCBContentHelper::Exists( aFileObj.GetMainURL( INetURLObject::DecodeMechanism::NONE ) ) )
+            bool exists;
+            try
+            {
+                exists = utl::UCBContentHelper::Exists( aFileObj.GetMainURL( INetURLObject::DecodeMechanism::NONE ) );
+            }
+            catch (const Exception&)
+            {
+                DBG_UNHANDLED_EXCEPTION("fpicker.office");
+                ErrorHandler::HandleError(ERRCODE_IO_GENERAL);
+                return;
+            }
+            if (exists)
             {
                 OUString aMsg = FpsResId(STR_SVT_ALREADYEXISTOVERWRITE);
                 aMsg = aMsg.replaceFirst(