fix(eval): partially port v8.2.3284

These were issues that I found while porting that I fixed upstream. :^)

Very little of the patch can be exactly ported as we're a bit behind on
dependant patches (we also can't use the exact :for emsg, as we don't
support iterating over Strings yet), so just translate the fixes as best
as we can for now.

Include latest relevant doc changes from:
- v8.1.0815
- v8.2.2658

src/nvim/eval.c

@@ -2614,7 +2614,7 @@ void *eval_for_line(const char_u *arg, bool *errp, char_u **nextcmdp, int skip)
         }
         tv_clear(&tv);
       } else {
-        EMSG(_(e_listreq));
+        EMSG(_(e_listblobreq));
         tv_clear(&tv);
       }
     }