TypeError: Cannot read property 'dependencies' of undefined

[EmilTholin]

[email protected] throws TypeError: Cannot read property 'dependencies' of undefined when certain attributes don't have explicit values. I'm not 100% sure what causes it, but this basic repro illustrates the issue.

This works great:

<Component exact={{true}} href="/cool"/>

This throws the error:

<Component exact href="/cool"/>

Stack trace

TypeError: Cannot read property 'dependencies' of undefined at error (/Users/emil/Code/svelte-dependencies-undefined/node_modules/rollup/dist/rollup.js:189:14) at Object.error (/Users/emil/Code/svelte-dependencies-undefined/node_modules/rollup/dist/rollup.js:17549:6) at promise.then.previous (/Users/emil/Code/svelte-dependencies-undefined/node_modules/rollup/dist/rollup.js:17558:32) at at process._tickCallback (internal/process/next_tick.js:188:7) at Function.Module.runMain (module.js:678:11) at startup (bootstrap_node.js:187:16) at bootstrap_node.js:608:3

[Rich-Harris]

Thanks — this is a fun bug. When Svelte walks the template, it does so with estree-walker, which builds up a map of child keys for each node type (e.g. an Element node has attributes and children properties). If the first example of a given node type has a misleading 'shape', it will get all the subsequent nodes of that type wrong unless you configure it — in this case, it was encountering an Attribute node with a value property that was true (i.e. not an object, and therefore not a 'child' property), and thus skipping value on all subsequent Attribute nodes. Fixed in #965!

[EmilTholin]

Awesome! Thanks Rich!