Impossible to solve the php problem

An error message appears at the top of my blog pages:

Warning: Trying to access array offset on value of type null in /home/jzsv5873/spiritalia.fr/wp-content/themes/blossom-fashion/inc/typography.php on line 313

Warning: Trying to access array offset on value of type null in /home/jzsv5873/spiritalia.fr/wp-content/themes/blossom-fashion/inc/typography.php on line 314

I went to the php code at these lines, it says this:
313. $ fonts [‘weight’] = $ weight_style [‘weight’];
314. $ fonts [‘style’] = $ weight_style [‘style’];

Before everything was fine, please help me solve the problem. How can I do ?
I thank you in advance.

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