minor fix failure management

bundles/fr.irisa.cairn.gecos.typeexploration/src/fr/irisa/cairn/gecos/typeexploration/dse/MinPlusOneExploration.java

@@ -83,6 +83,11 @@ public class MinPlusOneExploration extends AbstractExplorationAlgorithm {
 			logger.fine("Found best next (W Plus One) solution: " + solution.getID());
 		}
 		
+		if(!getAccuracy(solution).isPresent() || !getCost(solution).isPresent())
+			throw new NoSolutionFoundException("Failed to find a solution likely because the minimun precision "
+					+ "configuration of some Symbols is too low, resulting in errors (like divide by zero for example).\n"
+					+ "Try rerun after enabling pruning or increasing the minimum W values of some symbols.");
+		
 		if(!userAccuracyConstraint.isValid(solution))
 			throw new NoSolutionFoundException("No valid solution was found!");