More helpful error when trying to open a non file

This is not really correct e.g. vis /dev/zero will print a
misleading error.

1 files changed, 3 insertions, 1 deletions

diff --git a/text.c b/text.c
index 565505f..89e3512 100644
--- a/text.c
+++ b/text.c
@@ -664,8 +664,10 @@ Text *text_load(const char *filename) {
 			goto out;
 		if (fstat(txt->fd, &txt->info) == -1)
 			goto out;
-		if (!S_ISREG(txt->info.st_mode))
+		if (!S_ISREG(txt->info.st_mode)) {
+			errno = EISDIR;
 			goto out;
+		}
 		// XXX: use lseek(fd, 0, SEEK_END); instead?
 		txt->buf.size = txt->info.st_size;
 		if (txt->buf.size != 0) {