can-import can-tag fails silently when tag does not exist - P(4) ~5

[justinbmeyer]

From: canjs/canjs#1859

<can-import from="app/component/" can-tag="app-loading">
          <app-component></app-component>
</can-import>

If app-loading is not already imported, can-import will fail without throwing an error. It never renders app-component.

[Macrofig]

Found the unique use cases that cause this behavior

In all these use cases, the desired tag has not been previously registered with can-view-callbacks (specifically using this signature)

Special Characters

<can-import from="app/component/" can-tag="app-loading">
          <app-component></app-component>
</can-import>

No error is thrown and app-component never renders.

Solution

• Log an error using can-util.dev when attempting to load a tag that has not been registered.
• Render the content of can-import when promise is resolved

No Special Characters

can-component allows this but logs a warning.

<can-import from="app/component/" can-tag="loading">
          <app-component></app-component>
</can-import>

An error is thrown because can-view-callbacks.tag returns undefined and can-view-import expects a function. Also, app-component never renders.

Solution

• Log an error using can-util.dev when attempting to load a tag that has not been registered.
• Render the content of can-import when promise is resolved

Actual Implementation

• Check if tag exists or is valid
• If not valid/not exists, log warning
• It not valid/not exists, render content of can-import as if can-tag property did not exist.

The warning logs were resolved yesterday. Checking today how difficult it will be to render content when cat-tag value is invalid.

[phillipskevin]

closed by #57.