gapis/service: Fix internal errors not getting returned.
gapis/service: Fix internal errors not getting returned.

Previously we were returning (nil, nil) for internal errors.
This was causing a lot of crazy exceptions to be thrown by the client.

Qining/gapid,google/gapid,google/agi,google/agi,baldwinn860/gapid,pmuetschard/gapid,Qining/gapid,dsrbecky/gapid,google/gapid,google/gapid,Qining/gapid,google/gapid,pmuetschard/gapid,dsrbecky/gapid,dsrbecky/gapid,baldwinn860/gapid,google/gapid,dsrbecky/gapid,baldwinn860/gapid,google/gapid,baldwinn860/gapid,pmuetschard/gapid,google/agi,dsrbecky/gapid,Qining/gapid,baldwinn860/gapid,pmuetschard/gapid,google/agi,baldwinn860/gapid,google/agi,pmuetschard/gapid,Qining/gapid,pmuetschard/gapid,Qining/gapid,google/gapid,google/agi,google/agi,pmuetschard/gapid,Qining/gapid,dsrbecky/gapid,google/gapid,Qining/gapid,dsrbecky/gapid,google/agi,baldwinn860/gapid,dsrbecky/gapid,baldwinn860/gapid,pmuetschard/gapid