Missing template is unexpected exception and should NOT be silenced by using theme's default template

[pamtbaau]

A page referencing a non-existing template is, IMHO, an unexpected runtime exception. The developer should be notified about this exception.

This issue of non-existing templates could easily be caused by novice users evaluating different themes.

Since commit Added default templates in Grav itself #9880ce (18 Sep 2020), the exception has been silenced by using the theme's default or modular/default templates instead.

I think this is a less then optimal handling of exceptions.

I also don't see a use-case in which silencing the exception is deliberately depended upon.

Alternatives for silencing I could think of:

• Throw the error again. Which might break sites that deliberately depend on silencing the exception.
• Log the error and continue as is.
• When installing new theme, or switching between themes, check if pages reference non-existing templates.
• Add new check in Problem plugin checking for non-existing templates.
  • User could be asked if check should be run with option to never be asked again
• During upgrade check for missing templates.
  • User could be asked if check should be run with option to never be asked again.

[hughbris]

This explains some pages unexpectedly rendering without templates I've been seeing recently.

I can see pros and cons for this and probably depends on developer's philosophy. Could we make the behaviour a system toggle? Or standardise a YAML property like fallback_template into themes going forward?

[mahagr]

I think this would be a perfect change for Grav 2.0 with maybe the proposed option for 1.x.