This problem seems to be caused by the query parser.
The error message can be reproduced by the following procedure:
(open the attached project "test.xml". Notice, that there is an intentional
syntax error (space between "E" and "<>") in the query):
1. Load project test.xml;
2. Go to query tab and press "Model check". Then the error message "E: Unknown
identifier" appears (if one presses "Model check" again (not necessary for
reproducing the error) without changing anything, one is prompted with "syntax
error, unexpected T_GT" message);
3. Change the state space representation to "Options"->"State space
4. Press "Model check". Then error "CAUGHT EXCEPTION: Invalid variable type" is
prompted. It does not matter if the syntax of the query has been corrected or
not. If "Model check" is pressed again, "Fatal error: Broken pipe
The server connection has been killed." error message is prompted.
Created attachment 16 [details]
model for reproducing the error
This was actually caused by the fix for bug 58. The implicit declaration of the
unknown variable 'E' would modify the model, thus causing a crash when the model
is instantiated. A fix has been checked into CVS.