TypeError in assemble helpers

Question

Despite not using the filter helper in a template a TypeError is preventing assemble completing. It looks like the options parameter isn't being passed or is being passed as undefined.

Here's the stack trace:

Warning: Cannot read property 'data' of undefined Use --force to continue.
TypeError: Cannot read property 'data' of undefined
    at Object.helpers.filter (/home/tim/workspace/projects/severine/node_modules/assemble/node_modules/assemble-handlebars/node_modules/handlebars-helpers/lib/helpers/helpers-collections.js:357:15)
    at Object.eval (eval at <anonymous> (/home/tim/workspace/projects/severine/node_modules/assemble/node_modules/assemble-handlebars/node_modules/handlebars/lib/handlebars/compiler/compiler.js:564:23), <anonymous>:41:50)
    at Object.<anonymous> (/home/tim/workspace/projects/severine/node_modules/assemble/node_modules/assemble-handlebars/node_modules/handlebars/lib/handlebars/runtime.js:30:33)
    at Object.search (/home/tim/workspace/projects/severine/node_modules/assemble/node_modules/assemble-handlebars/node_modules/handlebars/lib/handlebars/compiler/compiler.js:1274:21)
    at Object.Handlebars.VM.invokePartial (/home/tim/workspace/projects/severine/node_modules/assemble/node_modules/assemble-handlebars/node_modules/handlebars/lib/handlebars/runtime.js:81:28)
    at Object.eval (eval at <anonymous> (/home/tim/workspace/projects/severine/node_modules/assemble/node_modules/assemble-handlebars/node_modules/handlebars/lib/handlebars/compiler/compiler.js:564:23), <anonymous>:86:17)
    at /home/tim/workspace/projects/severine/node_modules/assemble/node_modules/assemble-handlebars/node_modules/handlebars/lib/handlebars/runtime.js:30:33
    at /home/tim/workspace/projects/severine/node_modules/assemble/node_modules/assemble-handlebars/node_modules/handlebars/lib/handlebars/compiler/compiler.js:1274:21
    at Object.render (/home/tim/workspace/ae_projects/severine/node_modules/assemble/node_modules/assemble-handlebars/index.js:38:17)
    at Object.render (/home/tim/workspace/projects/severine/node_modules/assemble/lib/engine.js:87:17)

Aborted due to warnings.

If I comment out the body of the filter function, assemble runs normally.

Answer 1

@tim we usually see these errors when there's a conflict with a property name on the data context and a handlebars helper.

If you have filter as a property in your data context, try using {{this.filter}} instead of {{filter}} to give Handlebars a hint that it should be using the property instead of the helper.

This question is from this issue on Github. I hope this helps anyone else having the same issue.