24.2: Linter does not allow mandatory numeric parameter without value or value=""

[bernt-matthias]

Describe the bug

For instance here the TestsCaseValidation linter reports:

Serious problem parsing tool source or tests - cannot validate test cases. The exception is []

The exception comes from here.

I do not see a reason why this should not be possible. Probably the solution is

            if value:
                float_value = float(value)
-            elif optional:
-                float_value = None
-            else:
-                raise ParameterDefinitionError()
+           else:
+               float_value = None

I remember that the TS errors on tools with numeric parameters without value attribute, where the solution is to add value="" ... Which also never made sense to me. See #16960 and #16966

In addition the ParameterDefinitionError exceptions in this file should probably include a descriptive text and ideally the parameter name.

Galaxy Version and/or server at which you observed the bug
Galaxy Version: 24.2?

To Reproduce

lint the linked tool.