fix: memory limit issue for join filter, fix #737

Author: harttle

src/filters/array.ts

@@ -6,7 +6,7 @@ import type { Scope } from '../context'
 
 export const join = argumentsToValue(function (this: FilterImpl, v: any[], arg: string) {
   const array = toArray(v)
-  const sep = arg === undefined ? ' ' : arg
+  const sep = isNil(arg) ? ' ' : stringify(arg)
   const complexity = array.length * (1 + sep.length)
   this.context.memoryLimit.use(complexity)
   return array.join(sep)

test/e2e/issues.spec.ts

@@ -495,4 +495,10 @@ describe('Issues', function () {
     const liquid = new Liquid()
     expect(() => liquid.parse({} as any)).not.toThrow()
   })
+  it('Unexpected "RenderError: memory alloc limit exceeded" #737', () => {
+    const liquid = new Liquid();
+    const context = { x: ["a", "b"] };
+    const template = "{{ x | join: 5 }}"
+    expect(liquid.parseAndRender(template, context)).resolves.toEqual('a5b')
+  })
 })