Problem:

Adding a process instance duration report to a combined report crashes the combined report.

Steps to reproduce:

• Create a report with View: Process Instance, Measure: Duration (Avg), and Group By: None
• Save the report
• Create a new combined report
• Add the process instance duration to the combined report

Actual result :

Combined Report shows error message: "Cannot read property 'length' of undefined"

Expected result:

Combined Report shows a bar chart with the data of the process instance duration report