`graphql.resolve` crashes backend process on invalid `BigInt` filter value (`signal 6`, Postgres enters recovery)

Describe the bug
pg_graphql crashes a PostgreSQL backend process (SIGABRT / signal 6) when a GraphQL filter passes a non-numeric string to a BigInt field.

Instead of returning a GraphQL validation/coercion error, the backend process is terminated while running:

SELECT graphql.resolve($1, $2, $3)
After that, Postgres restarts and clients see recovery/pool errors

To Reproduce

1. Ensure a GraphQL-exposed type has a BIGINT column (in our case this is version).
2. Run this GraphQL operation through graphql.resolve:

query GetJobDetails($definitionFilter: jobDefinitionViewFilter, $runtimeFilter: jobsViewFilter) {
  jobDefinitionViewCollection(filter: $definitionFilter) {
    edges {
      node {
        id
        version
        displayName
      }
    }
  }
  jobsViewCollection(filter: $runtimeFilter, first: 1) {
    edges {
      node {
        state
      }
    }
  }
}

3. Use variables where the BigInt-typed filter value is not numeric:

{
  "definitionFilter": {
    "environment": { "eq": "dev" },
    "name": { "eq": "job-name" },
    "version": { "eq": "not-an-int" }
  },
  "runtimeFilter": {
    "environment": { "eq": "dev" },
    "name": { "eq": "job-name" }
  }
}

4. Observe PostgreSQL logs:
   • client backend ... was terminated by signal 6: Aborted
   • Failed process was running: SELECT graphql.resolve($1, $2, $3)
   • followed by recovery mode and pooler login failures.

Expected behavior
A clear and concise description of what you expected to happen.

The invalid BigInt input should return a normal GraphQL/SQL error (similar to invalid input syntax for type bigint) and should not crash the backend process.

Screenshots
If applicable, add screenshots to help explain your problem.

Versions:

• PostgreSQL: PostgreSQL 18.1 on aarch64-unknown-linux-musl, compiled by gcc (Alpine 15.2.0) 15.2.0, 64-bit
• pg_graphql commit ref: unknown in packaged build (extension version is 1.5.12)

Additional context

• Plain Postgres cast handles this correctly without crashing:
  • SELECT 'not-an-int'::bigint; -> ERROR: invalid input syntax for type bigint: "not-an-int"
• The crash appears specific to the graphql.resolve path.
• Observed app-side error after crash:
  • Lost connection to the database server.

Security
If you beleive you have identified a security vulnerability in pg_graphql, please follow the instructions at security.txt and wait for a response before opening a GitHub issue.