Description
When a Handlebars template contains decorator syntax referencing an unregistered decorator (e.g. ``), the compiled template calls lookupProperty(decorators, "n"), which returns undefined. The runtime then immediately invokes the result as a function, causing an unhandled TypeError: ... is not a function that crashes the Node.js process.
Recommendation
Update the handlebars package to the latest compatible version. Followings are version details:
- Affected version(s): >= 4.0.0, <= 4.7.8
- Patched version(s): 4.7.9
References
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See something that needs correcting? Let us knowUpdated March 30, 2026