Merge pull request #521 from mattgibbs/fix_embedded_display_crash_on_…

…open

Fix crash in case where base_path property isn't set.

pydm/widgets/embedded_display.py

@@ -154,6 +154,7 @@ def open_file(self, force=False):
             return
         # Expand user (~ or ~user) and environment variables.
         fname = os.path.expanduser(os.path.expandvars(self.filename))
+        full_fname = None
         if self.base_path:
             full_fname = os.path.join(self.base_path, fname)
         if not is_pydm_app():
@@ -175,7 +176,7 @@ def open_file(self, force=False):
         # If you get this far, you are running inside a PyDMApplication, load
         # using that system.
         try:
-            if os.path.isabs(full_fname) and os.path.exists(full_fname):
+            if full_fname and os.path.isabs(full_fname) and os.path.exists(full_fname):
                 w = self.app.open_file(full_fname, macros=self.parsed_macros())
             else:
                 w = self.app.open_relative(fname, self,