Make sure that types are frozen before creating the schema

[michael-georgiadis]

Description

Some interface types escape from the type freezing. That leads to the type being added in the schema, but whenever you try to validate the schema validation/generation tries to fetch the fields of an unfrozen type which leads to an exception of the MutableTrait.

This is referenced in the issue 308

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.82%. Comparing base (53f9d49) to head (d3305d4).
⚠️ Report is 138 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #789      +/-   ##
============================================
- Coverage     95.72%   94.82%   -0.91%     
- Complexity     1773     1855      +82     
============================================
  Files           154      175      +21     
  Lines          4586     4889     +303     
============================================
+ Hits           4390     4636     +246     
- Misses          196      253      +57     

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[oojacoboo]

@michael-georgiadis Thanks for this! Have a look at #790 I was working on at the same time as you, apparently. I saw your comment earlier that you'd deleted (Github sent it), and it got me thinking. Let me know your thoughts.

[michael-georgiadis]

Thanks man, closing this one then!