Fix bug in Rust relating to PlayedTile

The bug broke a contract that was relied on by WASM

src/game.rs

@@ -37,7 +37,7 @@ pub struct PlayerState {
 #[tsify(from_wasm_abi)]
 pub struct PlayedTile {
     pub index: usize,
-    pub character: char,
+    pub character: Option<char>, // we only set this if PlayedTile is a blank
 }
 
 #[derive(Debug, Serialize, Deserialize, Tsify)]
@@ -164,7 +164,15 @@ impl Game {
 
                 let coord = Coordinates::new_from_index(played_tile.index);
                 if letter.is_blank {
-                    letter.text = played_tile.character;
+                    match played_tile.character {
+                        None => {
+                            panic!("You can't play a blank character without providing a letter value")
+                        }
+                        Some(x) => {
+                            // TODO - check that x is a valid alphabet letter
+                            letter.text = x;
+                        }
+                    }
                 }
                 played_letters.push((letter, coord));
 

src/player_interaction/ai.rs

@@ -72,9 +72,14 @@ impl CompleteMove {
                         match m {
                             Some(x) => {
                                 if letter.partial_match(&x.letter) {
+                                    let character = if x.letter.is_blank {
+                                        Some(x.letter.text)
+                                    } else {
+                                        None
+                                    };
                                     played_tiles.push(Some(PlayedTile {
                                         index: x.coordinates.map_to_index(),
-                                        character: x.letter.text,
+                                        character,
                                     }));
                                     *m = None;
                                     found_match = true;