Issue description

When submitting a request that includes a 'vars' section the request succeeds but the dashboard fails with an error:

a.trim is not a function

I am using docker compose on a macbook: apache/apisix:3.14.1-debian
and the curl command with the vars statements:

"vars": [ [ "uri", "~~", "^/(.*)/v1beta/models/(gemini-3-pro-preview)(?::[A-Za-z0-9._-]+)?$" ] ]

Expected behavior

Display of the route without error.

How to Reproduce

1. docker compose:

apisix:
  image: apache/apisix:3.14.1-debian
  depends_on:
    - etcd
  volumes:
    - ./config/apisix/config.yaml:/usr/local/apisix/conf/config.yaml
  ports:
    - "${APISIX_HTTP_PUBLISHED_PORT}:${APISIX_HTTP_INTERNAL_PORT}"
    - "${APISIX_ADMIN_PUBLISHED_PORT}:${APISIX_ADMIN_INTERNAL_PORT}"
  restart: always
  networks:
    - company

2. execute curl command:

curl \
  -o curl-endpoint.out \
  -w "%{http_code}\n" \
  -X PUT http://127.0.0.1:9181/apisix/admin/routes/endpoint \
  -H "X-API-KEY: REDACTED" \
  -H "Content-Type: application/json" \
  -d '{
  "methods": [
    "GET",
    "POST"
  ],
    ... REDACTED
  "vars": [
    [
      "uri",
      "~~",
      "^/(.*)/v1beta/models/(gemini-3-pro-preview)(?::[A-Za-z0-9._-]+)?$"
    ]
  ]

3.In browser goto https://localhost:9181/ui/routes. Choose 'View' on the created route and and get the error 'a.trim is not a function'

Screenshots

No response

Environment

• apisix version (cmd: apisix version): 3.14.1
• OS (cmd: uname -a):Darwin Mac.lan 25.2.0 Darwin Kernel Version 25.2.0: Tue Nov 18 21:09:56 PST 2025; root:xnu-12377.61.12~1/RELEASE_ARM64_T6041 arm6
• OpenResty / Nginx version (cmd: nginx -V or openresty -V):
• etcd version, if have (cmd: run etcd --version):
• apisix-dashboard version, if have:
• Browser version, if have:

Additional context

No response