i originally thought this was an example of "strict liability" or "negligence" but its not. can someone help me identify the correct legal concept here?

design; the errors came from Part C. On August 25th, despite the mishaps in May and June, the restoration is almost complete. The crew was busy doing final cleaning, polishing, and decorating. The MNCPC decided it wanted to do a ceremony to commemorate the 95 year dedication of the cross over Labor Day weekend. This meant the crew had to not only complete the restoration, but also beautify the area for the ceremony. The crew decided that it needed to replace some of the sidewalk near the cross. Two crew members, Crosby Mason and Griffin Roberts, set to work. Old Time Restoration had recently purchased a new jack hammer called the Jack Extreme. This would be the company's first time using the new tool. As Griffin began jack hammering the concrete, things seemed to go smoothly However, as he increased the intensity of the tool, he noticed that it seemed to accelerate and apply more pressure than he intended. When he tried to reduce pressure, he could not. Crosby saw Griffin had a problem and came to help. However, the jack hammer jumped and went onto Crosby's foot. Thankfully, Crosby was wearing steel toe boots. The pressure from the tool did break Crosby's foot, requiring several surgeries to repair the damage. A few days after the event, Brady received a safety notice regarding the tool, That notice indicated that users were experiencing the problems that Griffin did when using it. Brady believes the Jack Extreme is unsafe