Add message if Geyser thinks the English locale is missing (#1825)

connector/src/main/java/org/geysermc/connector/utils/LanguageUtils.java

@@ -187,7 +187,11 @@ public class LanguageUtils {
         if (FileUtils.class.getResource("/languages/texts/" + locale + ".properties") == null) {
             result = false;
             if (GeyserConnector.getInstance() != null && GeyserConnector.getInstance().getLogger() != null) { // Could be too early for these to be initialized
-                GeyserConnector.getInstance().getLogger().warning(locale + " is not a valid Bedrock language."); // We can't translate this since we just loaded an invalid language
+                if (locale.equals("en_US")) {
+                    GeyserConnector.getInstance().getLogger().error("English locale not found in Geyser. Did you clone the submodules? (git submodule update --init)");
+                } else {
+                    GeyserConnector.getInstance().getLogger().warning(locale + " is not a valid Bedrock language."); // We can't translate this since we just loaded an invalid language
+                }
             }
         } else {
             if (!LOCALE_MAPPINGS.containsKey(locale)) {