Fix typos mostly in comments, docs and test names (GH-15209)

diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index 793ce92..a5f4c47 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -841,7 +841,7 @@
 
     /* Set carefully the position value. Alternatively, we could use the seek
        method instead of modifying self->pos directly to better protect the
-       object internal state against errneous (or malicious) inputs. */
+       object internal state against erroneous (or malicious) inputs. */
     position_obj = PyTuple_GET_ITEM(state, 1);
     if (!PyLong_Check(position_obj)) {
         PyErr_Format(PyExc_TypeError,