Make it work with flake.nix

src/ruby/process.cc

@@ -191,6 +191,15 @@ BarLine bar_contents(uint8_t mode, uint32_t width, std::string foldername,
   mrb_value mod_val = mrb_obj_value(C_module);
   mrb_value block = mrb_funcall(mrb, mod_val, "b_bar", 0);
   mrb_value val_line = mrb_funcall(mrb, block, "call", 1, info);
+  if (mrb_array_p(val_line) && RARRAY_LEN(val_line) == 1) {
+    val_line = mrb_ary_ref(mrb, val_line, 0);
+  }
+  if (!mrb_hash_p(val_line)) {
+    mrb_value inspected = mrb_funcall(mrb, val_line, "inspect", 0);
+    printf("bar returned: %s\n", RSTRING_PTR(inspected));
+    fprintf(stderr, "bar returned: %s\n", mrb_obj_classname(mrb, val_line));
+    abort();
+  }
   if (mrb->exc) {
     end_screen();
     fputs("Error when executing Ruby code:\n", stderr);
@@ -200,6 +209,11 @@ BarLine bar_contents(uint8_t mode, uint32_t width, std::string foldername,
   }
   mrb_value text_val = mrb_hash_get(
       mrb, val_line, mrb_symbol_value(mrb_intern_cstr(mrb, "text")));
+  if (!mrb_string_p(text_val)) {
+    fprintf(stderr, "text is not a string: %s\n",
+            mrb_obj_classname(mrb, text_val));
+    abort();
+  }
   const char *ptr = RSTRING_PTR(text_val);
   mrb_int len = RSTRING_LEN(text_val);
   bar_line.line = std::string(ptr, len);