pySim-shell: catch exceptions from walk() while exporting

When we run the exporter we also get an error summary at the end.
However, if walk() throws an eception this stops the exporter
immediately and we won't get the summpary. Lets catch exceptions from
walk as well so that we are able to end gracefully.

Change-Id: I3edc250ef2a84550c5b821a72e207e4d685790a5
diff --git a/pySim-shell.py b/pySim-shell.py
index 0ed4b7c..f498dea 100755
--- a/pySim-shell.py
+++ b/pySim-shell.py
@@ -648,10 +648,17 @@
         context = {'ERR': 0, 'COUNT': 0, 'BAD': [],
                    'DF_SKIP': 0, 'DF_SKIP_REASON': []}
         kwargs_export = {'as_json': opts.json}
+        exception_str_add = ""
+
         if opts.filename:
             self.export_ef(opts.filename, context, **kwargs_export)
         else:
-            self.walk(0, self.export_ef, None, context, **kwargs_export)
+            try:
+                self.walk(0, self.export_ef, None, context, **kwargs_export)
+            except Exception as e:
+                print("# Stopping early here due to exception: " + str(e))
+                print("#")
+                exception_str_add = ", also had to stop early due to exception:" + str(e)
 
         self._cmd.poutput(boxed_heading_str("Export summary"))
 
@@ -666,14 +673,14 @@
             self._cmd.poutput("#  " + b)
 
         if context['ERR'] and context['DF_SKIP']:
-            raise RuntimeError("unable to export %i elementary file(s) and %i dedicated file(s)" % (
-                context['ERR'], context['DF_SKIP']))
+            raise RuntimeError("unable to export %i elementary file(s) and %i dedicated file(s)%s" % (
+                    context['ERR'], context['DF_SKIP'], exception_str_add))
         elif context['ERR']:
             raise RuntimeError(
-                "unable to export %i elementary file(s)" % context['ERR'])
+                    "unable to export %i elementary file(s)%s" % (context['ERR'], exception_str_add))
         elif context['DF_SKIP']:
             raise RuntimeError(
-                "unable to export %i dedicated files(s)" % context['ERR'])
+                    "unable to export %i dedicated files(s)%s" % (context['ERR'], exception_str_add))
 
     def do_reset(self, opts):
         """Reset the Card."""