Bugfix: detect empty "per"s

setup.cfg

 [metadata]
 name = dsiParser
-version = 1.0.0
+version = 1.1.0
 description = Parse D-SI unit strings to LaTeX
 long_description = file: README.md
 

src/dsiParser.py

@@ -66,6 +66,12 @@ class dsiParser:
         tree = []
         warningMessages = []
         tree = dsiString.split(r"\per")
+        for subtree in tree:
+            if len(subtree) == 0:
+                warningMessages.append(_warn(r"The dsi string contains a \per missing a numerator or denominator! "+
+                        f"Given string: {dsiString}", 
+                        RuntimeWarning))
+                tree.remove(subtree)
         if len(tree) > 2:
             warningMessages.append(_warn(r"The dsi string contains more than one \per, does not "+
                         f"match specs! Given string: {dsiString}",