{} in an attribute list causes the compiler/linter to crash instead of producing a meaningful error

[CherryDT]

Describe the bug
{} in an attribute list causes the compiler/linter to crash instead of producing a meaningful error.

To Reproduce

<span {}></span>

https://svelte.dev/repl/e8b23903c76b4e9daf28185841799a87?version=3.35.0

The result is an exception TypeError: Cannot read property 'length' of null which doesn't really indicate what happened and where (in VSCode this shows at (1, 1)).

Expected behavior
A meaningful error like Variable name or spread operator expected.

Stacktraces

Stack trace

bundler.js:11 TypeError: Cannot read property 'length' of null
at read_attribute (compiler.js:16002)
at tag (compiler.js:15862)
at new Parser$1 (compiler.js:16787)
at parse$3 (compiler.js:16919)
at Object.compile (compiler.js:29918)
at Object.transform (bundler.js:11)
at bundler.js:11

• Svelte version: 3.35.0

[dummdidumm]

If this would parse and return as an entry in the list of warnings afterwards it would also help #4818

[Conduitry]

@dummdidumm What would you want it to parse as? The same as if it weren't there at all?

[dummdidumm]

Honestly I don't care, I just don't want it to abort parsing, which would improve editor intellisense 😄 treating it as if it weren't there at all makes the most sense to me.

[dummdidumm]

#6217 was merged, giving a more meaningful error for this situation. I'm not sure if we should close this now or keep it upon until we decide if this should be a warning in the future, or only do that in a more loose AST parsing mode, which would need to be implemented and which would help for #4818

[tanhauhau]

yes i think we can close this issue for now, given that we have a meaningful error now.

for improving editor intellisense developer experience, we can explore that in #4818