fix: Handle PatchFailed error in PATCH request

[7shi]

Currently, PatchFailed errors in PATCH requests are not properly handled, causing uncaught promise rejections:

plugin:obsidian-local-rest-api:57202 Uncaught (in promise) PatchFailed
    at applyPatch2 (plugin:obsidian-local-rest-api:57202:19)
    at RequestHandler.eval (plugin:obsidian-local-rest-api:57821:60)
    at Generator.next (<anonymous>)
    at fulfilled (plugin:obsidian-local-rest-api:70:24)

This PR adds error handling to properly catch and return these errors to the client, including the specific reason for patch failures in the API response.

The change wraps the applyPatch call in a try-catch block and uses the existing returnCannedResponse method to return a consistent error format.

[Shtooth]

Hello guys!
Any update on this?
It is really problematic to develop something that uses this as you need to completely restart the API each time you fail a request.

[coddingtonbear]

Sorry-- I have very limited time right now owing to it being the holidays, but I imagine I'll have a chance to look at this next week.