Catch mem-out on PTA module explore.

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@2221 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/pta/Modules2PTA.java

@@ -521,6 +521,7 @@ public class Modules2PTA
 		states.add(state);
 		explore.add(state);
 		src = -1;
+		try {
 			while (!explore.isEmpty()) {
 				// Pick next state to explore
 				// (they are stored in order found so know index is src+1)
@@ -588,6 +589,11 @@ public class Modules2PTA
 					}
 				}
 			}
+		}
+		// Catch a (possibly) common source of mem-out errors during explicit-state reachability
+		catch (OutOfMemoryError e) {
+			throw new PrismLangException("Out of memory after exploring " + (src + 1) + " states of module " + module.getName(), module);
+		}
 
 		// Set the invariant for the new module
 		moduleNew.setInvariant(invarNew);