OpenResFile and ResError weirdness when no resource file

[cornell@unix1.cs.umass.edu (Matthew Cornell)]

In MCL2.0b1p3 I'm opening resource files for PICTs and I stumbled upon
this situation (see the code below): There is no file named "foo" so
OpenResFile returns the -1 failure code as expected, but ResError
returns the noErr code!  I expected it to return resFNotFound or
something useful. I will be grateful for an explanation.

matt

? (with-pstrs ((file-name-ptr "foo"))
      (#_OpenResFile file-name-ptr))
-1
? (#_ResError)
0
?