patch 8.2.2208: Vim9: after reloading a script variable index may be invalid

patch 8.2.2208: Vim9: after reloading a script variable index may be invalid

Problem:    Vim9: after reloading a script variable index may be invalid.
Solution:   When the sequence number doesn't match give an error for using a
            script-local variable from a compiled function. (closes #7547)