fix: remove repeated error messages (#1011)

[harrisbisset]

I think this is removes the repeated error messages. Let me know if I've missed anything.

Example:

templ generate
(✗) Error [ error=failed to generate code for <file_here>: <file_here> parsing error: <p>: close tag not found: line 4, col 0 ]
(✗) Command failed: generation completed with 1 errors

Closes #1011

[joerdav]

Thanks for the contribution! Looks good to me.