As a relatively newer user of Qlik Sense, I find that Qlik's error messages are unhelpful, particularly in the load script and visualization function entry pages. When creating a load script or visualization, the error message "invalid expression" is overly broad and does not help identify what is causing the issue. The Help icon is great to look up a formula or syntax, but often in a large block of load text, or when trying out less familiar functions, the standard error messages are unhelpful and I personally spend hours trying to figure something out. The debugger tool similarly may show where an issue is causing an error, but gives little feedback on how to fix it.
Qlik should create a more detailed set of error messages that help users navigate the issue they are encountering, or perhaps use AI to guess what the user is trying to do and guide them in one or two directions to rectify the error. For example, if I have entered a "group by" clause that has an error, the error message could identify that I should be using an aggregation function, or that another function may be more helpful than "group by". This would especially help newer developers build experience in the platform more quickly.