patch 9.1.1219: Strange error with wrong type for matchfuzzy() "camelcase"

patch 9.1.1219: Strange error with wrong type for matchfuzzy() "camelcase"

Problem:  Strange error with type for matchfuzzy() "camelcase".
Solution: Show the error "Invalid value for argument camelcase" instead
          of "Invalid argument: camelcase" (zeertzjq).

Note that using tv_get_string() will lead to confusion, as when the
value cannot be converted to a string tv_get_string() will also give an
error about that, but "camelcase" takes a boolean, not a string.  Also
don't use tv_get_string() for the "limit" argument above.

closes: #16926

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>