you can either use alternative to GOOGLEFINANCE
(depends on what exactly are you up to)
or if you want to stick with it you can wrap it into IFERROR
:
=IFERROR(GOOGLEFINANCE(your_formula_here), GOOGLEFINANCE(same_formula_here))
or even:
=IFERROR(IFERROR(
GOOGLEFINANCE(your_formula_here),
GOOGLEFINANCE(same_formula_here)),
GOOGLEFINANCE(same_formula_here))