LoopAnalysis: isContiguousAccess fail gracefully

Existing implementation of isContiguousAccess asserts that one of the
function arguments is within certain range, depending on another parameter.
However, the value of this argument may come from outside, in particular in the
loop vectorization pass it may come from command line arguments.  This leads
to 'mlir-opt' crashing on an assertion depending on flags.  Handle the error
gracefully by reporting error returning a negative result instead.  This
negative result prevents any further transformation by the vectorizer so the IR
remains valid.

PiperOrigin-RevId: 227029496