fix: IndexError when editing the fitting range

Author: paulmueller

CHANGELOG

@@ -1,5 +1,5 @@
 0.5.6
- - maintenance release
+ - fix: IndexError when editing the fitting range
 0.5.5
  - maintenance release
 0.5.4

pyjibe/head/infdoublespinbox.py

@@ -56,7 +56,7 @@ def convert_string_to_float(string):
         val = float(string)
     except ValueError:
         string = string.strip()
-        if string[0] == "-":
+        if string.startswith("-"):
             asign = -1
         else:
             asign = 1