the state is saved. The function can save other state, modify values before
they're saved, etc.
-## Error handing
+# Error handing
-While a plugin can call ikiwiki's error routine for a fatal error, for
+While a plugin can call ikiwiki's `error` routine for a fatal error, for
errors that aren't intended to halt the entire wiki build, including bad
parameters passed to a [[PreProcessorDirective]], etc, it's better to just
return the error message as the output of the plugin.