notcurses_lex_scalemode(): return 0 on success

src/lib/notcurses.c

@@ -2352,8 +2352,10 @@ int notcurses_lex_scalemode(const char* op, ncscale_e* scalemode){
     *scalemode = NCSCALE_SCALE;
   }else if(strcasecmp(op, "none") == 0){
     *scalemode = NCSCALE_NONE;
+  }else{
+    return -1;
   }
-  return -1;
+  return 0;
 }
 
 const char* notcurses_str_scalemode(ncscale_e scalemode){

src/view/view.cpp

@@ -138,7 +138,8 @@ auto handle_opts(int argc, char** argv, notcurses_options& opts,
         break;
       case 's':
         if(notcurses_lex_scalemode(optarg, scalemode)){
-          std::cerr <<  "Scaling type should be one of stretch, scale, none" << std::endl;
+          std::cerr << "Scaling type should be one of stretch, scale, none (got "
+                    << optarg << ")" << std::endl;
           usage(std::cerr, argv[0], EXIT_FAILURE);
         }
         break;