added check "length ts > 1" before printing ambiguity warning in infer_types
added check "length ts > 1" before printing ambiguity warning in infer_types

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle