fix: bundle lint --format doesn't work properly (#406)

__tests__/bundle/bundle-lint-format/json-format-snapshot.js

@@ -0,0 +1,43 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`E2E bundle lint format bundle lint: should be formatted by format: json 1`] = `
+{
+  "totals": {
+    "errors": 1,
+    "warnings": 0,
+    "ignored": 0
+  },
+  "version": "1.0.0-beta.63",
+  "problems": [
+    {
+      "ruleId": "spec",
+      "severity": "error",
+      "message": "Expected type \`MediaType\` (object) but got \`null\`",
+      "suggest": [],
+      "location": [
+        {
+          "source": {
+            "ref": "openapi.yaml"
+          },
+          "pointer": "#/paths/~1my_post/post/requestBody/content/application~1json",
+          "reportOnKey": false
+        }
+      ]
+    }
+  ]
+}{
+  "totals": {
+    "errors": 0,
+    "warnings": 0,
+    "ignored": 0
+  },
+  "version": "1.0.0-beta.63",
+  "problems": []
+}
+❌ Validation failed with 1 error.
+run \`openapi lint --generate-ignore-file\` to add all problems to the ignore file.
+
+bundling ./openapi.yaml...
+📦 Created a bundle for ./openapi.yaml at /tmp/null.yaml <test>ms.
+
+`;