Ensure working code path on CPython

Author: ehrenfeu

src/imcflibs/imagej/misc.py

@@ -852,6 +852,8 @@ def save_script_parameters(
             # TODO: discuss if this approach is fine within Fiji/Jython
             try:
                 val = inputs.get(key)
+                if not val:  # required for testing in CPython
+                    raise KeyError("failure looking up value for '%s'" % key)
                 f.write("%s: %s\n" % (key, str(val)))
                 saved += 1
             except: