feat: enable stricter type checking options

feat: make the app more fault tolerant

src/lib/backup/backup.ts

@@ -95,6 +95,7 @@ export function restoreFromFile(
   switch (file.type) {
     case "backup": {
       const recent = file.history[0];
+      if (!recent) return;
       if (recent[1].device !== get(serialPort)?.device) {
         alert("Backup is incompatible with this device");
         throw new Error("Backup is incompatible with this device");
@@ -177,7 +178,7 @@ export function getChangesFromLayoutFile(file: CharaLayoutFile) {
   const changes: Change[] = [];
   for (const [layer, keys] of file.layout.entries()) {
     for (const [id, action] of keys.entries()) {
-      if (get(layout)[layer][id].action !== action) {
+      if (get(layout)[layer]?.[id]?.action !== action) {
         changes.push({
           type: ChangeType.Layout,
           layer,

src/lib/backup/compat/legacy-chords.ts

@@ -13,11 +13,11 @@ export function csvChordsToJson(csv: string): CharaChordFile {
       .map((line) => {
         const [input, output] = line.split(/,(?=[^,]*$)/, 2);
         return [
-          input
+          input!
             .split("+")
             .map((it) => KEYMAP_IDS.get(it.trim())?.code ?? 0)
             .sort((a, b) => a - b),
-          output
+          output!
             .trim()
             .split("")
             .map((it) => KEYMAP_IDS.get(SPECIAL_KEYS.get(it) ?? it)?.code ?? 0),

src/lib/backup/compat/legacy-layout.ts

@@ -17,7 +17,7 @@ export function csvLayoutToJson(
   for (const layer of csv.trim().split("\n")) {
     const [layerId, key, action] = layer.substring(1).split(",").map(Number);
 
-    layout.layout[Number(layerId) - 1][Number(key)] = Number(action);
+    layout.layout[Number(layerId) - 1]![Number(key)] = Number(action);
   }
 
   return layout;