'Illegal mix of collations' is raised instead of 'Invalid utf8mb3 character string'

I run this query intentionally injecting a bad utf8 byte sequence into the query body:

EXECUTE IMMEDIATE REPLACE("SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES"

                          " WHERE TABLE_NAME LIKE 't20xBEBE'",

                          '0xBEBE', 0xBEBE);

It returns a confusing error:

ERROR 1267 (HY000): Illegal mix of collations (utf8mb3_general_ci,IMPLICIT) and (utf8mb4_uca1400_ai_ci,COERCIBLE) for operation 'like'

It's true that the constant cannot be converted to utf8mb3, so utf8mb3_general_ci cannot be used for comparison in LIKE.

However, the error should be raised earlier, even before mixing collations for comparison.

ER_INVALID_CHARACTER_STRING would be fine, like the one raised in this query:

SELECT _utf8mb3 0xBEBE;

ERROR 1300 (HY000): Invalid utf8mb3 character string: 'BEBE'

The misleading error message makes it hard to debug user programs when a user program erroneously added wrong bytes, e.g. using snprintf() or similar function.