Metrics: misconfiguration leads to wrong temporality and no error message

[jmacd]

Description

When you configure the metrics basic.Processor with an AggregationTemporalitySelector that disagrees with the configured Exporter, it's possible for the exporter to receive the wrong data and no error message.

I observed this with the following configuration:

• basic.Processor given a StatelessAggregationTemporalitySelector (a.k.a. StatelessExportKindSelector).
• Prometheus exporter used, this exporter will see deltas and no error messages.

Related: #2274.

Expected behavior

This should return errors to the exporter. After View Configuration is implemented, it should not be possible to arrive in this configuration. See open-telemetry/opentelemetry-specification#2013

[MrAlias]

This issues relates to the current metric SDK. The metric SDK redesign project includes changes to the SDK design that will make this issue obsolete. I'm closing so no wasted work is performed to address this.