better errors

src/libventi/cache.c

diff --git a/src/libventi/cache.c b/src/libventi/cache.c
index 8dcb52f..be0d6ac 100644
--- a/src/libventi/cache.c
+++ b/src/libventi/cache.c
@@ -424,7 +424,6 @@
 	vtcachenread++;
 	n = vtread(c->z, score, type, b->data, c->blocksize);
 	if(n < 0){
-		werrstr("vtread %V: %r", score);
 		if(chattyventi)
 			fprint(2, "read %V: %r\n", score);
 		b->iostate = BioVentiError;

src/libventi/file.c

diff --git a/src/libventi/file.c b/src/libventi/file.c
index 9b25011..04605da 100644
--- a/src/libventi/file.c
+++ b/src/libventi/file.c
@@ -1036,7 +1036,7 @@
 
 	vtfilegetentry(f, &e);
 	if(count < 0 || offset < 0){
-		werrstr("vtfilewrite: bad offset or count");
+		werrstr("bad offset or count");
 		return -1;
 	}