test: tighten diagnostics and execution tree assertions

Co-authored-by: aarne <82001+aarne@users.noreply.github.com>

Author: Copilot

packages/bridge-core/test/execution-tree.test.ts

@@ -48,6 +48,7 @@ describe("ExecutionTree edge cases", () => {
     tree.logger = { warn: (msg: string) => (warning = msg) };
 
     assert.equal((tree as any).applyPath([{ x: 1 }], ref(["x"])), undefined);
+    assert.equal((tree as any).applyPath([{ x: 1 }], ref(["0", "x"])), 1);
     assert.match(warning, /Accessing "\.x" on an array/);
   });
 });

packages/bridge/test/bridge-format.test.ts

@@ -1289,8 +1289,8 @@ describe("parser diagnostics and serializer edge cases", () => {
     const result = parseBridgeDiagnostics("version 1.5\nbridge Query.x {\n  with output as o\n  o.x = \"ok\"\n}\n§");
     assert.ok(result.diagnostics.length > 0);
     assert.equal(result.diagnostics[0]?.severity, "error");
-    assert.ok(result.diagnostics[0]?.range.start.line != null);
-    assert.ok(result.diagnostics[0]?.range.start.character != null);
+    assert.equal(result.diagnostics[0]?.range.start.line, 5);
+    assert.equal(result.diagnostics[0]?.range.start.character, 0);
   });
 
   test("reserved source identifier is rejected as const name", () => {