Added a check on unknown ESC command at compilation time (#438)

addons/escoria-core/game/core-scripts/esc/esc_compiler.gd

@@ -219,6 +219,7 @@ func _compile(lines: Array) -> Array:
 			returned.append(dialog_option)
 		elif command_regex.search(line):
 			var command = ESCCommand.new(line)
+			if command.is_valid():
 				escoria.logger.trace("Line is the command %s" % command.name)
 				returned.append(command)
 		else: