Better Error Handling
I'm not sure if this is an existing feature but there should be a better way to handle errors in Power BI Desktop like indicating out which columns are causing an error and what value.
Currently, PBI will say that there is an error (e.g. DataFormat.Error) but won’t indicate which columns are causing them. Testing the columns one by one is such a waste of time especially when working on a large amount of data. Removing Errors feature is also not of help.
Sharon Maxon commented
The Power Query screen highlights some errors and notes the step where the error is happening; other errors and performance hits can impact the query refresh and they are not highlighted. Any error or design problem that causes refresh to slow dramatically should be highlighted.
Olivier Travers commented
Power BI definitely needs better error handling, whether in Power Query on the desktop, or during refreshes in the service. To your point about errors in data sources, you can use Power Query to restructure "keep errors" results, but it's way too much work for something that should be built in:
The Power BI service is often very unhelpful if there is a problem with data in the report. The error is too broad. It may be helpful to Microsoft's support team, but it isn't helpful to the developers at organizations encountering these problems. I would hope Microsoft would implement better error handling sooner rather than later.