fix(parser): fix empty array and nested bracket parsing

Improve the `ValueParser` to correctly disambiguate between empty
arrays `[]` and the start of nested structures. This ensures that
the parser can distinguish between an array containing a single
element that starts with a bracket and an actual empty array.

Update tests to reflect that parsed tuples are returned as arrays
rather than objects.

src/csv-loader/tests/parseCsv-combinators.test.ts

@@ -183,16 +183,8 @@ describe("parseCsv - references in combinatory schemas", () => {
 
     const cactusEnemies = result.data[0].enemies as unknown[];
     expect(cactusEnemies).toHaveLength(2);
-    expect(cactusEnemies[0]).toEqual({
-      name: "仙人掌怪",
-      hp: 12,
-      effects: [],
-    });
-    expect(cactusEnemies[1]).toEqual({
-      name: "仙人掌怪",
-      hp: 12,
-      effects: [],
-    });
+    expect(cactusEnemies[0]).toEqual(["仙人掌怪", 12, []]);
+    expect(cactusEnemies[1]).toEqual(["仙人掌怪", 12, []]);
 
     // Second row: snake_pair
     expect(result.data[1]).toMatchObject({
@@ -206,13 +198,13 @@ describe("parseCsv - references in combinatory schemas", () => {
 
     const snakeEnemies = result.data[1].enemies as unknown[];
     expect(snakeEnemies).toHaveLength(1);
-    expect(snakeEnemies[0]).toEqual({
-      name: "蛇",
-      hp: 10,
-      effects: [
-        { effect: "poison", stacks: 2 },
-        { effect: "quick", stacks: 1 },
+    expect(snakeEnemies[0]).toEqual([
+      "蛇",
+      10,
+      [
+        ["poison", 2],
+        ["quick", 1],
       ],
-    });
+    ]);
   });
 });

src/value-parser.ts

@@ -304,9 +304,23 @@ class ValueParser {
       if (!elementIsTupleOrArray) {
         this.consume();
         hasOpenBracket = true;
-      } else if (this.input[this.pos + 1] === "[") {
+      } else {
+        // Element is tuple or array - need to disambiguate
+        // Save position to check if this is an empty array
+        const savedPos = this.pos;
         this.consume();
+        this.skipWhitespace();
+        if (this.peek() === "]") {
+          // Empty array []
+          this.consume();
+          return [];
+        } else if (this.peek() === "[") {
+          // Nested brackets [[ - this is the array opener
           hasOpenBracket = true;
+        } else {
+          // [ belongs to the first element, restore position
+          this.pos = savedPos;
+        }
       }
     }
 
@@ -324,7 +338,8 @@ class ValueParser {
     const result: unknown[] = [];
     while (true) {
       this.skipWhitespace();
-      result.push(this.parseValue(schema.element, false));
+
+      result.push(this.parseValue(schema.element, elementIsTupleOrArray));
       this.skipWhitespace();
 
       if (!this.consumeStr(";")) {