- Improved error handling: any Scyther errors now raise an exception.

This can be dealt with accordingly. If no error occurs, we can just
  nicely assume the output is a claim list or something similar.

gui/Scyther/Error.py

@@ -9,6 +9,22 @@ class Error(Exception):
     """Base class for exceptions in this module."""
     pass
 
+class ScytherError(Error):
+    """Exception raised for errors generated by the backend
+
+    Attributes:
+        errorlist -- list of error lines are retrieved from the
+        backend
+    """
+
+    def __init__(self, errorlist):
+        self.errorlist = errorlist
+
+    def __str__(self):
+        s = "Scyther backend reported the following errors:\n"
+        s = s + "\n".join(self.errorlist)
+        return s
+
 class InputError(Error):
     """Exception raised for errors in the input.