Currently, we store the ranges that are to be used for e.g. combined date reports in the `ExecutionContext` and refer to this range when evaluating a combined report only, for single report we do not use the range in the context but rather calculate one when needed. Especially with the addition of custom number variable reports which also specify a range for combined reports, there are now multiple instances where we check if this range exists - if so, use the range and if not, evaluate the min. and max. Stats to set the needed range for a single report.
Instead of calculating the ranges for single and combined reports in different places and then checking mid-evaluation which one is the appropriate to use, it would be nice to refactor this logic to default to always store the range in the `ExecutionContext` and use that range for both combined and single report evaluation.
- There is no differentiation in logic between range settings of combined and single reports, so that ranges for date and number variable reports are calculated and stored in one place only