Prevent crash for invalid characters

Author: SilkeSchomann

src/mslice/presenters/cut_widget_presenter.py

@@ -114,8 +114,16 @@ def _parse_input(self):
             e_units,
         )
 
-        intensity_start = self._cut_view.get_intensity_start()
-        intensity_end = self._cut_view.get_intensity_end()
+        try:
+            intensity_start = float(self._cut_view.get_intensity_start())
+        except ValueError:
+            intensity_start = None
+            warnings.warn("Invalid intensity start parameter")
+        try:
+            intensity_end = float(self._cut_view.get_intensity_end())
+        except ValueError:
+            intensity_end = None
+            warnings.warn("Invalid intensity end parameter")
 
         norm_to_one = bool(self._cut_view.get_intensity_is_norm_to_one())
         width = self._cut_view.get_integration_width()

src/mslice/widgets/workspacemanager/input_boxes.py

@@ -50,4 +50,16 @@ def __init__(self, is_bose=False, parent=None):
     def user_input(self):
         v1 = self.edit1.text()
         v2 = self.edit2.text()
-        return float(v1) if v1 else None, float(v2) if v2 else None
+        v1_value = None
+        v2_value = None
+        if v1:
+            try:
+                v1_value = float(v1)
+            except ValueError:
+                pass
+        if v2:
+            try:
+                v2_value = float(v2)
+            except ValueError:
+                pass                
+        return v1_value, v2_value