User:SkSlick/templates/error

Can be tested for by {{#iferror:value|then|else}}.

 @ Template:ChkArg
{{#if:
 {{{1|}}}
 |{{{1}}}
 |⁠{{User:SkSlick/templates/error
 |No argument provided
 }}
}}

 @ Template:Example
{{#iferror:
 {{subst:ChkArg
 |{{{1|}}}
 }}
 |<!--leave empty to pass error along-->
 |The count is {{{1|}}}.
}}

 @ anywhere
{{Example|10}}

The count is 10.

 @ anywhere
{{Example}}

Template error: No argument provided
 Source: {{Example}}