improved user feedback in GUI when fitting fails due to incomplete data

src/MagicFormulaTyreTool.m

@@ -418,12 +418,12 @@ function onStartFittingRequested(app, ~, ~)
 
             fig = app.UIFigure;
             title = 'Tyre Model Fitter';
-            message = sprintf(['To start fitting, the following conditions ' ...
+            msg = sprintf(['To start fitting, the following conditions ' ...
                 'must be met:' newline() ...
                 '\t- Tyre model loaded' newline() ...
                 '\t- Tyre data loaded' newline() ...
                 '\t- Fit modes selected (Fx0, Fy0, Fx, ...)']);
-            showUserFail = @(x) uialert(fig, message, title, 'Icon', 'error');
+            showUserFail = @(x) uialert(fig, msg, title, 'Icon', 'error');
 
             tyreModel = app.TyreModel;
             if isempty(tyreModel)
@@ -446,10 +446,10 @@ function onStartFittingRequested(app, ~, ~)
             fitter.Measurements = measurements;
             fitter.FitModes = fitmodes;
 
-            message = 'Starting Fitter...';
+            msg = 'Starting Fitter...';
             dlg = uiprogressdlg(fig, ...
                 'Title', title, ...
-                'Message', message, ...
+                'Message', msg, ...
                 'Indeterminate','on', ...
                 'Cancelable', 'on');
 
@@ -472,28 +472,50 @@ function onStartFittingRequested(app, ~, ~)
                 close(dlg)
 
                 if cancelByUser
-                    message = 'Fitting process aborted by user.';
+                    msg = 'Fitting process aborted by user.';
                     icon = 'info';
                 else
-                    message = 'Fitting process successful.';
+                    msg = 'Fitting process successful.';
                     icon = 'success';
                 end
-                message = [message newline() ...
+                msg = [msg newline() ...
                     'Parameters of last iteration written to table.' ...
                     newline() newline() ...
                     'Details printed to logfile/console.'];
-                uialert(fig, message, title, 'icon', icon)
+                uialert(fig, msg, title, 'icon', icon)
             catch ME
                 paramsFitted = magicformula.v62.Parameters.empty;
                 e = events.TyreModelFitterFinished(paramsFitted);
                 notify(app.TyreModelPanel, 'TyreModelFitterFinished', e)
 
                 close(dlg)
 
-                message = ['Fitting process FAILED!' newline()...
-                    'Details printed to logfile/console.'];
-                uialert(fig, message, title, 'icon', 'error')
+                cause = ME.cause;
+                if iscell(cause)
+                    cause = cause{1};
+                end
 
+                msg = ['Fitting process FAILED!' newline() newline()];
+                switch class(cause)
+                    case 'exceptions.NoMeasurementForFitMode'
+                        fitmode = cause.FitMode;
+                        msg = [msg 'Cause:' newline() ...
+                            'Loaded measurements do not contain ' ...
+                            'data for selected fitmode ''%s''. ' ...
+                            newline() newline() ...
+                            'Troubleshooting:' newline() ...
+                            'Note that to fit ''Fx0'' ' ...
+                            'you require data that includes slip ratio ' ...
+                            'sweeps. Fitting ''Fx'' also requires slip ' ...
+                            'angle to be present during those sweeps. ' ...
+                            'Similarly, fitting ''Fy0'' requires slip ' ...
+                            'angle sweeps and ''Fy'' also requires ' ...
+                            'those sweeps at interval-fixed slip ratios.'];
+                        msg = sprintf(msg, fitmode);
+                    otherwise
+                        msg = [msg 'Details printed to logfile/console.'];
+                end
+                uialert(fig, msg, title, 'icon', 'error')
                 rethrow(ME)
             end
         end