software/theia: Fix null parameters templating

Before this commit, instance parameters that have a default null value
in JSON format were rendered as 'None' string in instance-theia.cfg.

In particular, Theia frontends were always requested with unsolvable
SLA parameters that prevented a frontend from ever being allocated:
```
sla-instance_guid = None
```

software/theia/buildout.hash.cfg

@@ -15,7 +15,7 @@
 
 [instance-theia]
 _update_hash_filename_ = instance-theia.cfg.jinja.in
-md5sum = 942e269192d284e563a84ae710c0595b
+md5sum = 09df701afb9a2e3927f42a71976bf03d
 
 [instance]
 _update_hash_filename_ = instance.cfg.in

software/theia/instance-theia.cfg.jinja.in

@@ -140,7 +140,9 @@ return = domain secure_access
 name = {{ parameter_dict['frontend-name'] }}
 software-url = {{ parameter_dict['frontend-sr'] }}
 software-type = {{ parameter_dict['frontend-sr-type'] }}
+{%- if parameter_dict.get('frontend-guid') %}
 sla-instance_guid = {{ parameter_dict['frontend-guid'] }}
+{%- endif %}
 
 {% if additional_frontend %}
 [remote-additional-frontend]
@@ -148,7 +150,9 @@ sla-instance_guid = {{ parameter_dict['frontend-guid'] }}
 name = {{ parameter_dict['additional-frontend-name'] }}
 software-url = {{ parameter_dict['additional-frontend-sr'] }}
 software-type = {{ parameter_dict['additional-frontend-sr-type'] }}
+{%- if parameter_dict.get('additional-frontend-guid') %}
 sla-instance_guid = {{ parameter_dict['additional-frontend-guid'] }}
+{%- endif %}
 {% endif %}
 
 
@@ -444,11 +448,13 @@ template =
       $${slapos-standalone-config:ipv6} \
       $${slapos-standalone-config:port} \
       $${slapos-standalone-config:computer-id} \
-      {% if parameter_dict.get('embedded-sr') %} \
+      {%- if parameter_dict.get('embedded-sr') %}
       --sr='{{ parameter_dict['embedded-sr'] }}' \
+      {%- if parameter_dict.get('embedded-sr-type') %}
       --srtype='{{ parameter_dict['embedded-sr-type'] }}' \
+      {%- endif %}
       --srparams='$${embedded-instance-parameters:rendered}' \
-      {% endif %} \
+      {%- endif %}
       $${slap-connection:server-url} \
       $${slap-connection:computer-id} \
       $${slap-connection:partition-id} \

software/theia/software.cfg

@@ -135,7 +135,7 @@ initialization =
     standalone.request(
         args.sr,
         "Embedded Instance",
-        args.srtype or None,
+        args.srtype,
         partition_parameter_kw=params,
     )