Fix error message

Author: hypergonial

arc/command/option/custom/emoji.py

@@ -55,7 +55,7 @@ def _convert_value(self, value: str) -> hikari.Emoji:
             return hikari.Emoji.parse(value)
         except ValueError as exc:
             raise OptionConverterFailureError(
-                self, value, f"Option '{self.name}' expected a valid color, got {value!r}."
+                self, value, f"Option '{self.name}' expected a valid emoji, got {value!r}."
             ) from exc
 
     @classmethod