implement lenientIf for the unless tag, too

src/builtin/tags/unless.ts

@@ -22,7 +22,7 @@ export default {
 
   render: function * (ctx: Context, emitter: Emitter) {
     const r = this.liquid.renderer
-    const cond = yield new Expression(this.cond).value(ctx)
+    const cond = yield new Expression(this.cond, ctx.opts.lenientIf).value(ctx)
     yield (isFalsy(cond, ctx)
       ? r.renderTemplates(this.templates, ctx, emitter)
       : r.renderTemplates(this.elseTemplates, ctx, emitter))

src/liquid-options.ts

@@ -19,7 +19,7 @@ export interface LiquidOptions {
   strictFilters?: boolean;
   /** Whether or not to assert variable existence.  If set to `false`, undefined variables will be rendered as empty string.  Otherwise, undefined variables will cause an exception. Defaults to `false`. */
   strictVariables?: boolean;
-  /** Modifies the behavior of `strictVariables`. If set, a single undefined variable will *not* cause an exception in the context of the `if` tag and the `default` filter. Instead, it will evaluate to `false` and `null`, respectively. Irrelevant if `strictVariables` is not set. Defaults to `false`. **/
+  /** Modifies the behavior of `strictVariables`. If set, a single undefined variable will *not* cause an exception in the context of the `if`/`elsif`/`unless` tag and the `default` filter. Instead, it will evaluate to `false` and `null`, respectively. Irrelevant if `strictVariables` is not set. Defaults to `false`. **/
   lenientIf?: boolean;
   /** Strip blank characters (including ` `, `\t`, and `\r`) from the right of tags (`{% %}`) until `\n` (inclusive). Defaults to `false`. */
   trimTagRight?: boolean;