If you assign a string*[] value to a string[] variable, e.g. with:
    string[] my_variable = my_g_variant.get_strv();
there is no warning, but Vala generates C code to free every member of the array. Looking at the type and documentation for Variant.get_strv(), this is incorrect, and results in double-frees of every member of the array.

Vala should throw a type error if the user attempts such an assignment.

This is with Vala 75359c3cab2e979d087ce0a19735bf86add33b42.