improve error handling in BaseEnv

Summary

(Summarize the bug encountered concisely.)

Explain your context

(Explain what you did.)

What is the expected correct behavior? What was your goal?

def _observations(self) -> np.ndarray:
        """Determine the observations list from environment state. This uses state_config to determine all
        observations.

        :return: Observations for the agent as determined by state_config.
        """
        assert self.state_config is not None, "Set state_config before calling _observations function."
        try: 
            obs = np.array([self.state[name] for name in self.state_config.observations], dtype=np.float64)
         except ValueError as e:
            raise ValueError("Could not find all observations in state.") from e
        return obs

What is the current bug behavior?

(What actually happens.)

Was there an error message?

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to format console output, logs, and code, as it's very hard to read otherwise.)

Steps to reproduce

(How one can reproduce the issue - this is very important)