fix error throwing in save message

[owenboy9]

Description

fix error thrown on saving translation
prior to the fix, on click on save, it only kept 'thinking' forever

Changes

replace 'throw' with a return error message object

Notes to reviewer

thank you for all your help
tested the issue by changing the if statement to if (true) in order to see the error no matter what

Related issues

Resolves #146

[WULCAN]

Thank you, I approve of merging this pull request. I've noted a couple of further improvements that I think we will want to do, but we can defer those to a later pull request.

[WULCAN]

This was the only use of MessageNotFound

lyra/webapp/src/errors.ts

Lines 7 to 11 in ae85208

	export class MessageNotFound extends Error {
	constructor(lang: string, msgId: string) {
	super(`Message ${msgId} for language ${lang} not found`);
	}
	}

Removing the last usage is an excellent opportunity to also remove the unused source code. I believe unused source code makes the project harder to maintain.

Let's remember to remove MessageNotFound after merging this pull request.

[WULCAN]

The value for errorMessage is what will be displayed to the user.

lyra/webapp/src/components/MessageForm.tsx

Lines 279 to 286 in ae85208

	<Alert
	onClose={onDismissSnackbar}
	severity="error"
	sx={{ width: '100%' }}
	variant="filled"
	>
	{state.errorMessage}
	</Alert>

'Failed to update translation' is not a very helpful error message to the user. What can she do with that information? Still, it is much better than the save button just animating forever.

Let's remember to improve this further after merging this pull request.