Handle things better if VASSAL is configured, but not Java :-/

vasl_templates/webapp/main.py

@@ -2,6 +2,7 @@
 
 import os
 import json
+import logging
 
 from flask import request, render_template, jsonify, send_file, redirect, url_for, abort
 
@@ -30,7 +31,11 @@ def get_startup_msgs():
         _check_versions = False
         # check the VASSAL version
         from vasl_templates.webapp.vassal import VassalShim
-        VassalShim.check_vassal_version( startup_msg_store )
+        try:
+            VassalShim.check_vassal_version( startup_msg_store )
+        except Exception as ex: #pylint: disable=broad-except
+            # NOTE: We can get here is VASSAL has been configured, but not Java - don't show an error to the user :-/
+            logging.warning( "Can't get the VASSAL version: %s", ex )
 
     # collect all the startup messages
     startup_msgs = {}

vasl_templates/webapp/vassal.py

@@ -312,7 +312,10 @@ class VassalShim:
                 # NOTE: Using CREATE_NO_WINDOW doesn't fix the problem of VASSAL's UI sometimes appearing,
                 # but it does hide the DOS box if the user has configured java.exe instead of javaw.exe.
                 kwargs["creationflags"] = 0x8000000 # nb: win32process.CREATE_NO_WINDOW
-            proc = subprocess.Popen( args2, **kwargs )
+            try:
+                proc = subprocess.Popen( args2, **kwargs )
+            except FileNotFoundError as ex:
+                raise SimpleError( "Can't run the VASSAL shim (have you configured Java?): {}".format( ex ) )
             try:
                 proc.wait( timeout )
             except subprocess.TimeoutExpired: