hivex_value_type: Returns -1 on error. Fix documentation.

diff --git a/generator/generator.ml b/generator/generator.ml
index e1e957a..5a0ab6e 100755 (executable)
--- a/generator/generator.ml
+++ b/generator/generator.ml
@@ -990,7 +990,7 @@ On error this returns NULL and sets errno.\n\n"
        | RLenType ->
            pr "\
 Returns 0 on success.
-On error this returns NULL and sets errno.\n\n"
+On error this returns -1 and sets errno.\n\n"
        | RLenTypeVal ->
            pr "\
 The value is returned as an array of bytes (of length C<len>).