Partially undo commit 016c558d7, 2019-05-01

If sacles for plotting differ, issue a warning.
Skip this plot command only, when strict_errorhandling is set.

src/frontend/plotting/plotit.c

@@ -903,9 +903,14 @@ plotit(wordlist *wl, char *hcopy, char *devname)
         int firstscalelength = vecs->v_scale->v_length;
         for (d = vecs; d; d = d->v_link2)
             if (firstscalelength != d->v_length) {
-                fprintf(cp_err, "\nError: length of vector %s and its scale differ.\n", d->v_name);
-                fprintf(cp_err, "   cannot plot!\n");
-                goto quit;
+                fprintf(cp_err, "\nWarning: length of vector %s and its scale differ.\n", d->v_name);
+                /* Do not plot when strict_errorhandling is set */
+                if (ft_stricterror) {
+                    fprintf(cp_err, "   Cannot plot!\n");
+                    goto quit;
+                }
+                else
+                    fprintf(cp_err, "   Check the plot data!\n");
             }
     }