In the case where the cached context had been cleared the km_core_state_context_set_if_needed call would just compare the null terminations of both strings and not set the cached context to the application context.

I first thought I could just change the decrement of the pointers to occur before the iteration not after e.g.

for(; context_p > context && cached_context_p > cached_context; --context_p, --cached_context_p) {
    if(*context_p != *cached_context_p) {
      // The cached context doesn't match the application context, so it is
      // invalid
      return false;
    }
  }

This skips the comparing the null, however it will still also drop out and return true. It is just quicker to bail if the cached context is an "empty" string.
I also considered renaming is_context_valid to is_context_update_needed.

@keymanapp-test-bot skip