Made TextScriptProc return 0 if it encounters an unknown command

This is what the original game does

src/TextScr.cpp

@@ -1236,8 +1236,7 @@ int TextScriptProc()
 
 						//MessageBoxA(0, str_0, "エラー", 0);
 
-						gTS.p_read += 4;
+						return 0;
-						return 1;
 					}
 				}
 				else