Bad error message from unsupported attribute type

[duncanpo]

If an attribute of unsupported type is specified (ex. datetime), a cryptic error is thrown. The resulting error message is uninformative and doesn't indicate what the error is.

tr = opentelemetry.trace.getTracer("tracer");
attrs = dictionary("Current Time", datetime("now"));
startSpan(tr, "Span", Attributes=attrs);

Error using gateway
Can't convert the Array to this TypedArray

Error in  .  (line 63)
                [varargout{1:nargout}] = libmexclass.proxy.gateway("MethodCall", obj.ID, methodName, methodArgs);

Error in opentelemetry.trace.Tracer/startSpan (line 125)
            id = obj.Proxy.startSpan(spname, contextid, spankind, starttime, ...

[duncanpo]

Fix is in main branch