const golang.org/x/tools/internal/typesinternal.UndefinedOp

2 uses

	golang.org/x/tools/internal/typesinternal (current package)
		errorcode.go#L458: 	UndefinedOp
		errorcode_string.go#L56: 	_ = x[UndefinedOp-45]

The pages are generated with Golds v0.4.9. (GOOS=linux GOARCH=amd64)