fix: shows missing macro parameters

[pedrolamas]

Fixes issue introduced with #524, were a macro parameter with no default value would not show up in the interface.

Tested with the following example:

[gcode_macro TEST]
gcode:
  {% set A = params.A | default(0, true) | float %}
  {% set B = params.B | int | default(0.005, true) | float %}
  {% set C = params.C | default("PLA", true) %}
  {% set D = params.D | default("PLA") %}
  {% set E = params.E | int | default(0.2) %}
  {% set F = params.F %}

Before (F missing):

After (F showing):

Signed-off-by: Pedro Lamas [email protected]

[matmen]

LGTM, just one line that could be simplified ;)