wf: explicitly crash when temporary export files cannot be created (#45565)

wcs/wf/export_to_model.py

@@ -69,8 +69,8 @@ try:
     subprocess.check_call(['which', 'libreoffice'], stdout=subprocess.DEVNULL)
 
     def transform_to_pdf(instream):
+        temp_dir = tempfile.mkdtemp()
         try:
-            temp_dir = tempfile.mkdtemp()
             with tempfile.NamedTemporaryFile(dir=temp_dir) as infile:
                 while True:
                     chunk = instream.read(100000)