Describe the bug
Found when testing #3505

Running a fit with polydisperse parameters checked adds an error column to the polydisp table.
This is OK when just running the fit - the min/max/npts/nsigs/function combobox columns get shifted and display ok.
But when a model is changed AFTER the fitting, the table is not properly reindexed.

The table headers are correctly not displaying the error, but the parameter values still contain the error column.
This means Min now shows the error, Max shows the min value etc. Function is now showing the value of Nsigs and Filename contains the combobox of functions.

To Reproduce
Steps to reproduce the behavior:

1. Load a file
2. Choose a model
3. Check Polydispersity
4. In the PD tab - select one (or more) parameters
5. Run fitting
6. Observe a new column "Error" in the PD table
7. Change a model in the parameters tab
8. Go back to the PD tab
9. The headers are set correctly but the parameters still contain the error column and their layout is incorrect

Expected behavior
The error column should be removed

Screenshots

SasView version (please complete the following information):

• Version: 6.1 but present in earlier versions

Operating system (please complete the following information):

• OS: Windows 10