the turning speed is too slow for me, i coudn't make the turn to shoot any target ;(((
I think you didn't multyply Time.deltaTime for your movements?
without it there will be different movement speeds with different framerates in different computers ;o (if you use the update function which updates per frame)
maybe try speed*Time.deltaTime

super cool idea! the game is addictive XD

try this and rebuild the game, this will ignore error and let u continue the game in browser

1. Open your project in the Unity Editor.
2. From the Unity Editor menu, select Edit > Project Settings.
3. Under Publishing Settings, set Enable Exceptions to Full Without Stacktrace.

reference:
https://www.reddit.com/r/Unity3D/comments/zscwai/3d_unity_webgl_error_runtimeerr...

i think u got bug, if u can't fix but game still can run u can do this:

1. Open your project in the Unity Editor.
2. From the Unity Editor menu, select Edit > Project Settings.
3. Under Publishing Settings, set Enable Exceptions to Full Without Stacktrace.
   

https://www.reddit.com/r/Unity3D/comments/zscwai/3d_unity_webgl_error_runtimeerr...