Previously, formatters were freed by LUA code when re-opening outputs.
Since now, outputs are not controlling anymore the falco_formats class (see #1412), we just free formatters only if were already initialized.
That is needed when the engine restarts (see #1446).
By doing so, we also ensure that correct inspector instance is set to the formatter cache.
Signed-off-by: Leonardo Grasso <me@leonardograsso.com>
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