feat(web): add async solver worker

src/lib/solver.rs

@@ -75,7 +75,7 @@ impl Solver {
             - new_possible_solutions.equal_likelieness_entropy();
 
         if new_possible_solutions.len() == 0 {
-            return Err("Solution space is empty".to_string());
+            return Err("Applying this guess would empty the solution space!".to_string());
         }
 
         self.possible_solutions = new_possible_solutions;