strans is broken

[hombit]

I tried the following query from documentation examples on PostgreSQL server 9.6.15, 10.10 and 11.5 and PostgreSQL client 10.10:

SELECT theta( strans '20d,30d,40d,XZY' ) * 180 / pi() AS theta;

For each case I've obtained wrong result, moreover two consecutive executions sometimes give different results, for instance 2.66762880858253e-308 and 2.66762880856011e-308. I've run tests on 9.6.15 as described in readme, they've passed.