[ssr] anomaly -> error (Fix #8253)
[ssr] anomaly -> error (Fix #8253)

Looks like this bug was introduced when unification started raising the
UnableToUnify exception in 8ac929ea128f1f7353b3f4d532b642e769542e55 .
I now turn this exception into a PretypeError that is correctly catched
and printed.

SkySkimmer/coq,Zimmi48/coq,maximedenes/coq,ppedrot/coq,ejgallego/coq,silene/coq,Zimmi48/coq,coq/coq,JasonGross/coq,silene/coq,coq/coq,gares/coq,ppedrot/coq,Zimmi48/coq,JasonGross/coq,maximedenes/coq,SkySkimmer/coq,Matafou/coq,ppedrot/coq,gares/coq,JasonGross/coq,ppedrot/coq,gares/coq,ejgallego/coq,ejgallego/coq,coq/coq,ppedrot/coq,SkySkimmer/coq,Matafou/coq,gares/coq,SkySkimmer/coq,maximedenes/coq,coq/coq,ejgallego/coq,maximedenes/coq,Matafou/coq,gares/coq,silene/coq,Zimmi48/coq,maximedenes/coq,JasonGross/coq