catch ValueError that is raised on axis editor data that cannot be cast to float

Author: chrissimpkins

src/slice/__main__.py

@@ -551,7 +551,21 @@ def btn_clicked_slice(self):
             self.statusbar.update()
             # must keep this return statement to abort execution!
             return
-        elif not self.fvar_table_model.instance_data_validates_missing_data():
+
+        # validate axis editor instance values
+        # returns True/False response for test of
+        # at least one instance value
+        # raises ValueError on attempt to cast to float
+        # if the entry is a non-numeric value
+        try:
+            instance_values_are_present = (
+                self.fvar_table_model.instance_data_validates_missing_data()
+            )
+        except ValueError as e:
+            SliceErrorDialog(f"{e}")
+            return
+
+        if not instance_values_are_present:
             SliceErrorDialog(
                 "You requested the same design space that is supported in the "
                 "font path that you are processing. Please define at least one "

src/slice/models.py

@@ -288,7 +288,7 @@ def get_instance_data(self):
                 except ValueError:
                     raise ValueError(
                         f"'{axis_value}' is not a valid {axistag} axis value. "
-                        f"Please enter a valid value and try again."
+                        f"Please enter a single numeric value and try again."
                     )
 
         return instance_data
@@ -298,7 +298,10 @@ def instance_data_validates_missing_data(self):
         # axis tag with a defined instance, and False if all
         # axis tags have blank entry fields = the original variable
         # font that the user entered
-        return len(self.get_instance_data()) != 0
+        try:
+            return len(self.get_instance_data()) != 0
+        except ValueError as e:
+            raise e
 
     def get_default_axis_value(self, axistag):
         if axistag in self.fvar_axes: