createPatch & createTwoFilesPatch throw meaningless exceptions if structuredPatch returns undefined #463
Description
Example:
> diff.createPatch("file1", "foo\nbar\n", "foodie\nbarbell", undefined, undefined, {maxEditLength: 1})
Uncaught TypeError: Cannot read properties of undefined (reading 'oldFileName')
at formatPatch (/home/mark/jsdiff/lib/patch/create.js:241:12)
at createTwoFilesPatch (/home/mark/jsdiff/lib/patch/create.js:270:10)
at Object.createPatch (/home/mark/jsdiff/lib/patch/create.js:274:10)
We should propagate the failure that structuredPatch has signalled to us (by way of returning undefined) in a more useful way.