Error: Fit requires the curve fitting toolbox

[ftadel]

Creating a ROI without the Curve Fitting Toolbox installed causes this error:

Check for missing argument or incorrect argument data type in call to function 'fit'.

Error in SimMEEG_GUI_v21a>plot_source_waves (line 2886)
    ft=fit(h.tfr_ROI(v).h(tfr_idx).UserData.roi.x_roi',h.tfr_ROI(v).h(tfr_idx).UserData.roi.sig_amp','linearinterp'); xwin=ft(h.cfg.study.lat_sim);     % windowing freq waves

Error in SimMEEG_GUI_v21a>selected_ROI (line 2555)
    plot_source_waves();

Error in SimMEEG_GUI_v21a>bl_rbbox_gca_v2 (line 2539)
    btn.Button=1; selected_ROI(h.tfr_ROI(v).h(tfr_idx),btn); % automatically plotting window function
 
Error while evaluating UIControl Callback.

Since this is not among the most widely used toolboxes, it would be good to have an alternative for it.