Custom Error Handling

[pgierz]

We need to have some custom error messages to better handle typical user issues:

• Choose blocks
• variable expansions

@dbarbi: maybe we can add to this list

An idea would be:

class EsmParserError(Exception):
   pass # PG: Still need to figure out how this works. See ScriptEngine for an example...

raise EsmParserError("A choose block was not used correctly...")

[pgierz]

Just checked ScriptEngine, it does exactly this:

"""ScriptEngine exceptions
"""

class ScriptEngineStopException(Exception):
    """Raise this exception when ScriptEngine should stop"""

So, we can put a custom error message like I showed above and at least throw our own errors rather than relying on the Python built-in ones.