patch 8.2.3194: Vim9: argument types are not checked at compile time

Problem:    Vim9: argument types are not checked at compile time.
Solution:   Add several more type checks, simplify some. (Yegappan
            Lakshmanan, closes #8598)
diff --git a/src/job.c b/src/job.c
index 7607f7b..89d7756 100644
--- a/src/job.c
+++ b/src/job.c
@@ -1726,7 +1726,7 @@
     char_u	*text;
 
     if (in_vim9script()
-	    && (check_for_string_or_number_arg(argvars, 0) == FAIL
+	    && (check_for_buffer_arg(argvars, 0) == FAIL
 		|| check_for_string_arg(argvars, 1) == FAIL))
 	return;