Arms: fix aim-120 maddog bug

[BobDotCom]

This PR fixes a bug where missiles launched in maddog mode freeze mid-air due to an undefined attribute. This seems to have been caused by b13ffb3aef3138fbf6b457475bbe4ee76a4a9ca6.

Related:

• https://discord.com/channels/379782363061813248/496121096492417025/1090344903512440835
• https://discord.com/channels/379782363061813248/496121096492417025/1091361542374703115
• https://discord.com/channels/379782363061813248/496121096492417025/1098148782778089472